I'm a relatively new player (9 months), Free to Play, and have the three fusion tokens ready to swap.  I was initially going to save them until I had 5-6 and do Wixwell+Titus back to back, in case they get nerfed or I pull them naturally.  I wasn't expecting them to make a 'bad' fusion right when players hit 3 tokens, so I'm reevaluating that decision.

The account has been overall quite lucky.  My roster is strong enough to beat almost all dungeons at Hard 10.  I can 2 key UNM Clan Boss (I have 1 keyed before, so I have quick battle), so I don't need help there at all.  My Chimera and Hyrdra are a bit behind where they could be, but I haven't put in the time to optimize those teams fully and my clan struggles to defeat the higher difficulty stages anyway.

I enjoy pvp, but feel quite good with my roster.  When I lose pvp matches, It feels like the overpowering stats on my opponents gear is the most limiting factor - not having access to a 'correct' champion to counter what they're doing.  It's quite common to beat people who are more progressed than me, and I almost never lose to players who are less progressed.  This makes Fabian slightly less attractive to me, although I ban him almost 100% of the time my opponent picks him.

My gear is overall quite strong for a 9 month account I would think.  All max level champions are in 6-star gear, with optimized main stats and somewhat mediocre substats in most cases.  I assume at this point I just need to keep pulling the lottery lever when farming for events and upgrade my gear slowly that way.

My main 3 champions I'm considering are: Fabian, Wixwell, and Gnut.  I've heard Titus is likely not worth going for until you get Wixwell (although the likelihood I pull him is much lower than the others).  I'm also open to going for any other champions, as long as they impact an aspect of the account in a meaningful way.

Quick Breakdown of Progress:  
2 Key UNM clan boss (with access to quick battles)  
68M Brutal Hydra  
53M Brutal Chimera  
Finished normal Faction Wars, just starting Hard mode  
Full clear Doom Tower every month every rotation  
Full clear Grim Forest every month (sometimes can't beat some purple stages at the end)  
Struggle in hard mode Cursed City and later stages of Normal  
Hard 10 farming at 98%+: Ice Golem, Dragon, Spider's Den, Phantom Shogun  
Hard 6 Fire Knight progression (waiting for Marius missions to keep pushing)  
Stage 20 Sand Devil (need to min-max Embrys for a solo build for 25)  
Gold III live arena (will def hit Gold IV once I do more games)  
Silver IV Tag Team arena  
Can get into Plat arena, but never finished there

Overall, the account only really feels "held back" in Chimera, Hyrdra, and Cursed City.  I'd imagine pushing for Hard 10 Fire Knight will take quite a bit of trial and error, and may not even be currently possible with the gear/champions.  This is the main thing making me lean towards Gnut, although I'm quite certain ill get hard stuck being unable to beat Hard Mode Amius for a while, even if I do secure Hard 10 Fire Knight.

Strangely, the 'pain point' of the account mostly feels like the lack of nuker capability.  Mikey carried that category for a long time.  I built Kassandra a few months ago when pulling her soul, and she's the main champion I lean on for this job now (even though most people say she's mediocre).

Any suggestions would be greatly appreciated.  I'm consuming as many suggestions of others as possible, but this account feels rather unique and many of their suggestions don't fully apply.

I don't have any big souls for any of the champions I would fuse (Picture included).  I just obtained the strong champions that are unleveled, just needing a 'break' in the constant events to get time to level them.  Obviously I'm excited for Lydia and Talenna.

Deciding Who To Swap for the Upcoming Fusion