I mostly judge characters as units, so apologies if some unit viability stuff leaks into my reasoning, I'm trying to not just axe the 10 worst units in the game though
I'd say I'd probably remove like
1. Garret (generic Berserker guy)
2. Douglas (generic General, at least the other Knights have meme status)
3. Geese (despite the fact that I've used him he's kinda forgettable)
4. Dayan (who even goes to Sacae lol, besides that he's just another bow user when you already have up to 4 Snipers, 2 Nomad Troopers and 3 Warriors using bows)
5. Juno (just another flying unit when you already have 4, Zeiss has some meme status and is kinda sorta an Est so he gets a pass)
6. Fae (sorry Fae fans, but I always forget I even have her until like Dragon Temple, and even then I just tend to use her as a mini-convoy)
7. Treck (he just dies way too easily in Chapter 7, plus he's easily the worst potential Paladin in the game, Marcus, Allen and Lance all have perfect availability, with Marcus being dang near essential early on in Hard Mode, Jerrot and Noah both start at a higher level and Noah has an extra point of Con iirc, and well Perceval is Perceval)
8. Cath (just a third Thief, is honestly a bit of a pain to deal with and it is arguable that it is better to kill her in Chapter 6 than to bother recruiting her)
9. Fir (kinda generic Myrmidon, especially considering the other two in this game have meme status and Rutger is legitimately one of the best units in this game)
10. Ogier (just a worse Deke, and he doesn't really have much meme status as far as I can tell)
Honestly a lot of these choices were hard for me, though I've definitely succeeded at not just axing the 10 worst units in the game 😄