I keep seeing posts where people ask who to spend their biometrics selectors on and I end up saying a lot of the same thing about how difficult various characters are to farm. The intent of this post is to summarize some of the data from /u/hecaitomix's spreadsheet, as well as changes since it was posted.

Also, check out u/qfuw's Guide (with Farmability / Rarity Ranking). The Google Spreadsheet that he built makes it very easy to figure out how farmable characters are for you, if you just make a copy of it and update it with your own data.

Impossible to Farm

These characters are not eligible for selection with character or generic biometric selectors (though class-specific ones work), nor is there any way in the game, other than BattleWorld or buying team packs that include them, to acquire their biometrics. You can't even get them through the Warp Device or through Dimension chests. However, they are eligible for rank-up tickets and are a good choice for them.

• Sister Grimm (Nico)
• She-Hulk
• Singularity

Unless you specifically like her, Singularity is generally not recommended as a good choice for rank-up tickets, due to being very weak in most modes.

Almost Impossible to Farm

Unlike characters in the "Impossible to farm" category, characters in this category are available primarily through Battleworld, but their biometrics can also be acquired via the Warp Device, Villain Siege, and generic biometric selectors.

• Jessica Jones
• Silk
• Spider-Gwen
• Spider-Man (Miles Morales)

Very Difficult to Farm

These characters can only be acquired via random means, and the average number that you can acquire in a given day is very low (1 per day or less, on average):

• Malekith: 0.7 biometrics per day
• Angela: 0.77 biometrics per day
• Black Cat: 0.77 biometrics per day
• Rocket Raccoon: 0.77 biometrics per day
• Star-Lord: 1 biometric per day

Of these characters, Malekith is a solid choice, though he's very good in 3-star Battleworld. Angela is also solid in the 3-star Battleworld.

Difficult to Farm

This includes a few different categories of characters: those who are exclusively shifters in Special missions; those who are exclusively available in Rifts; and those who only have 1 Story mission. Using selectors on these characters is recommended unless you're trying to 6☆ a more difficult character. I recommend against using rank-up tickets on these characters if you care about any of the rarer characters - at least, until you've ranked up those rarer characters.

• Ant-Man (Ally shifter in two Special missions)
• Wasp (Ally shifter in two Special missions and in Chaos chests)
• Destroyer (rift)
• Thor (rift and one story mission)
• Loki (rift)
• Black Panther (a rift and one story mission)
• Black Bolt (enemy shifter, one story mission, Honor chests)
• Gamora - honor tokens
• Warwolf - honor tokens
• Captain Marvel - honor tokens
• Red Hulk - honor tokens

A Bit More Difficult Than Average to Farm

On average, you can net 7 or so biometrics per day for these characters.

• Kingpin (2 story, honor chest, enemy shifter)
• Venom (2 story missions + ally shifter + chaos chest)

Average Difficulty to Farm

This is where most characters fit in, due to having 3 or so story missions or being able to be selected directly for Chaos or Honor Tokens. Most of these characters also have ally or enemy shifters in normal missions (chapters 1-8 for non-AoS characters). I recommend against using selectors on them, but buying their biometrics with crystals is okay, if you're impatient. War Machine is the only top-tier character I have experience with in this section, but I think several other characters here are worthy of investment: uniformed Falcon, Daredevil, Quake, Sif, and Deathlok. Luke Cage is supposedly top-tier (8/10) but I haven't ranked him up yet, so I can't comment.

Some of these characters are impossible for new players to farm. If you really want Sif, Quake, or Deathlok, it makes sense to consider them to be in the "Difficult to Farm" category, since you'll need a 5☆ or 6☆ character before you can get to them.

• War Machine
• Falcon
• Daredevil
• Elektra
• Luke Cage
• Winter Soldier
• Punisher
• Blade
• Hawkeye
• Hulk - chaos tokens
• Hulkbuster - chaos tokens
• Elsa - chaos tokens
• Lash - chaos tokens
• Deathlok - chapter 9&10
• Daisy Johnson (Quake) - chapter 9&10
• Sif - chapter 9&10
• Phil Coulson - chapter 9&10
• Lincoln Campbell - chapter 9&10

Slightly Easier than Average to Farm

I would apply the same advice to these characters that I would to the average difficulty characters. Green Goblin is top tier, but only if you play him manually. Doc Ock is worth investing in if you have his uniform.

• Green Goblin (3 story missions, enemy shifter, Chaos chest)
• Doc Ock (3 story missions, enemy shifter, Chaos chest)
• Red Skull (3 story missions, enemy shifter, Chaos chest)
• Bullseye (3 story missions, enemy shifter, Honor chest)
• Sharon Carter (3 story missions, ally shifter, Honor chest)

Easy to Farm

These characters all have at least 3 story missions and, except for IM, BW, and Mockingbird show up in a rift. I recommend not buying their biometrics or using selectors on them in general.

• Vision (also an ally shifter in a special mission)
• Spider-man
• Captain America
• Blade
• Hawkeye
• Ghost Rider
• Iron Fist (also in honor chests; only 2 story missions, but his rift drops the dodge booster, so you'll want to run it a lot regardless)
• Mockingbird (4 story missions, ally shifter, Chaos chest)
• Black Widow (4 story missions, enemy shifter)
• Iron Man (4 story missions, enemy shifter)

Very Easy to Farm

Any character with a special mission goes here. These characters actually require more energy per biometric than story mission characters, but you can unlock them very quickly if you focus on them. They are all solid characters, but you should not use biometric selectors or spend crystals buying their biometrics anyway, given how easy they are to farm. You can get an average of around 25 bios per day for these characters if you run X-5 for your normal runs and X-4 for your two unlimited runs (depending on how many times you can run X-4 during an unlimited run).

• Yellowjacket
• Groot
• Nebula
• Yondu
• Ronan
• Drax

Incredibly Easy to Farm

These characters have a special mission and more. Giant-man and Ultron are both solid characters, but you shouldn't use biometric selectors or spend crystals buying their biometrics anyway, given how easy they are to farm.

• Giant-man (is an ally shifter on his own special mission: average 41 bios per day)
• MODOK (3 specials and 3 story missions: average 34 bios per day)
• Ultron (2 specials, ally shifter in story missions, 3 story missions, chaos chests: average 38.5 bios per day)

So who should I get with my biometric selector?

Alternatively: Who should I get with my 5☆ Character Selector

It is important to point out that if you already have a character, using the 5☆ Character Selector on him/her will net you 128 bios and will not rank the character up to 5☆. Generic bio selectors and character selectors are also not usable on members of the A-Force.

If you want a rare character who is powerful, who you wouldn't mind being stuck at a particular rank, my recommendations are:

• Jessica Jones (Combat) - I wouldn't say that she's amazing, but she is, as another user put it, "competent." And outside of Battleworld, it's extremely difficult to find her bios.
• Angela (Universal) - recommended to keep at 3☆
• Gamora (Speed) - Good at 3☆; currently mid-tier at 6☆. Expected to improve with her upcoming uniform and 6☆ skill. Competes with Warwolf for bios. I currently recommend him over her, but she's a close second, particularly if you don't have other Speed heroes.
• Ant-man (Speed) - if you plan to farm Giant-man and Yellowjacket, Ant-man is solid. He starts being good at 5☆.
• Wasp (Blast) - if you plan to farm Giant-man and Yellowjacket or Giant-man and Ultron, Wasp has a good team-up with them. She also has really good leadership.
• Sister Grimm (Blast) <- Blast selectors only. SG is the best character in the A-Force and has an upcoming uniform.
• She-Hulk (Combat) <- Combat selectors only. SH is one of the top 3 Combat characters and she's amazing in 3☆ Battleworld with her uniform.

If you want a powerful character who you can continue to farm up without too much difficulty, my recommendations are:

• Loki (Universal) - if you plan to farm him to 6☆.
• Black Panther (Combat) - he's a top tier Combat character who is good in 3☆ Battleworld and also very good at 5☆-6☆.
• Venom (Combat) - with his uniform, Venom is a beast.
• Kingpin (Combat / Blast) - Kingpin is not my cup of tea, but he's good both without his uniform and gets even better with it
• Warwolf (Combat) - He's a strong combat character once you get him to 6☆, and he isn't bad at any rank prior to that. He has one of the better Passive abilities.
• Elsa (Speed) - Elsa's DPS isn't great, but she's very fun to play. Once you master her, she can be very good.

If you just want a powerful character who will carry you, and don't care that he or she is relatively easy to farm:

• Vision (Blast / Universal) - buy his uniform
• Groot (Combat) - once you get him to 3☆, you can use his healing circle to heal up the rest of your team, which will enable you to beat fights you'd otherwise get stuck on
• War Machine (Blast)
• Green Goblin (Speed) - if you're going to play manually and kite, GG is amazing. He's also very, very good in 3☆ Battleworld- so much so that I'm keeping him at 3☆ even though I could rank him up to 6☆.

Also, the first time that you lose a mission, you'll receive a free 3☆, level 30 character. Good choices for this character are Spider-man, Green Goblin, Vision, or War Machine. As u/SoDamnShallow has pointed out, you'll run into a lot of Yellowjackets in timeline battle, and GG and SM are both good counters to him.