Returning to the Hobby after a loooong absence.

Hi All,

I used to play way back in 2ed 40k and a very short while after 3e 40k was released. Life intervened, and Ive been away from the hobby ever since. Ive just discovered that an acquaintance of mine plays the new edition, and there is a small group of people at teh local game store with regular games happening.

Anyway - way back in 2e I played Tyranids, and was rather good at getting the devouring space monsters to eat everyone in my path. I no longer have any of the old mini's, and am looking for a new army to play (Not tyranids).

After doing a little research, I like the look of the following sets of minis, but would like some advice on what to play or collect. I like the idea of a shooty army, and dont want to play Imperial Guard (seems like too many models to have to pick up and paint to get started and while I like the fluff, I like some of the aesthetic of teh below a bit better.)

So... any advice or thoughts on if these are competitive, and how these armies play? Im looking for a force that allows me to pick up and paint some cool models, and still have it be competitive without having to cheese things out too much. Id also rather avoid a horde style army. I will probably start with a force aimed at like 500 points, then slowly build it out. I think local players are doing regular 1000 pt games so that is a target point value for a starting army and I could probably do 500 points with my acquaintance.

ANyway here is who I am considering and thoughts so far:

Dark Angels : I like the fluff, and it seems like a wide variety of units and models to paint. Id probably go for a mixed force - some deathwing, some ravenwing, and some of the normal green armored units. I like the gothic styling and they seem like they could be competitive without being overly optimized. Are they competitive as a mixed force?

Deathwatch : I really like the look of the kill teams, and they seem really interesting to paint and model, same with the gunship transport thing I dont remember the name of. But the rest of the army seems just kind of Meh. Will they get a codex?

Adeptus Mechanicus : I love the 50s style robots (Kastelan?) - the kastelans look awesome, as do the knights, the skitarii look OK. Their army list seems kind of... average and like they dont have a great variety - will games with them get stale since they seem like a smaller list of options for units? Is it important that they dont have psykers? I like the red black white silver and gold color schemes. Are they competitive? I also hear there is a new box set coming out, but I am not interested in the necrons, so Id have to either ebay them or have them sit in a box/waste money. How feasible/Unfair/useless is it to field a knight in smaller games?

Tau : I see there is a codex coming out in a week or so. I really like the Macross/Robotech/other anime style battlesuits. From the index it looks like a lot of chaff and a couple undercosted units though... are they reasonable with a mixed force? How reasonable is it to field some of the battlesuits as the core of your army and still be both competitive and not overpowered?

Any further thoughts or recommendations are appreciated.

Note:
Ive read a bunch of the articles here: https://1d4chan.org/wiki/Warhammer_40,000/Tactics/

And while the info is useful, its hard to evaluate since I havent played the game in so long.

Thanks in advance!