Oh! Favorite FE character time! My favorite!
My number one is Tiki, but especially Awakening Tiki. I think she's grown up quite a lot and matured in a lot of interesting ways ever since her first appearance. She's sort of a celebrity and holy figure, but would prefer to be modest and be 'normal'. She's lived for several thousand years and has outlived almost everyone she's ever known, but does her best to keep pushing forward. And because of her 'wise outside, kid on the inside' kind of attitude we great a great mix of her being silly and playful like the old days, but also more serious touching moments as well. It also helps that she actually got a handful of supports instead of being locked to 'Robin and only Robin' like the other characters post-Act 1 and was already established from previous games.
Another favorite of mine is Rennac from Sacred Stones. The whole L'Arachel gang cracks me up, but Rennac is one of the funniest 'straight man' characters I've seen. The poor guy just can't catch a break, can't be taken seriously by anyone, and just doesn't want to be here in the first place (Best example? When you're fighting the final boss, the big bad demon king that towers over every character, all the other characters have inspiring oneliners...Rennac on the other hand? "Come on...you can't be serious!") He's just a really nice change of pace from a lot of the heroic characters we get, a guy who's only here to get paid and even then doesn't want to do his job.
And now Shamir from Three Houses, she really took me by surprise. At first I wasn't sure I'd really like her all that much, she's rough around the edges when you interact with her in the monastery. But once I recruited her just to add to my headcount, I started using her more and more and she really grew on me with how much she opened up, how surprisingly sweet she could be to Byleth and Catherine (with mixing snark in), and how quickly I wanted her to keep talking about her backstory and herself.
Rapid fire for ones I don't have as much to talk about: Legion, hilariously weird, super simple guy, interesting gimmick all makes him a memoriable minor boss (He's so unique, we should make a profile for him some day). Knoll, I just can't help but feel bad for him, he's like a kicked puppy of a dark mage. Noire, very similar to Knoll, I just feel awful for her, and Awakening turns her suffering into a punchline, it just makes me feel bad. Eirika, Sacred Stones was my first FE, she's my first lord, I've got a personal bias for her now. Laegjarn, Laevatein, Helbindi, and Eir from Heroes...Never thought I'd be compelled by mobile game characters, but since Book 2 I've been liking the original cast more and more, Book 2 in particular is when I liked Heroes original cast most, Muspell for some reason had some of the most sympathetic cast members yet for me (Especially Helbindi, I didn't think I was going to like him as much as I did), and of course the Annas, I just can't not like the Annas.
...There's a bunch I like but these are the ones that stood out that I felt I had enough to talk about.