Favorite character would be Setsuka, but specifically her Soul Calibur 6 outfit. I always liked her as a character, but her SC6 design was what cemented her in the favorite category. Liking a design in The Soul Calibur series can sometimes be cursed, since they have a tendency of giving them such radical outfits they might as well be a different character altogether (Tira being the most egregious example)

However... when it comes to a character to
play, that's a different story entirely. Setsuka's main strength is her ability to fish for counterhits in neutral. She has overall one of the lowest startups in the game for her moves, which combined with SC6 making counterhit trigger on sidesteps, makes her pretty powerful. But in return for her strengths, her guard stamina damage and space control leaves a lot to be desired, making her actual pressure when she's in the advantage state kinda weak.
Pressure is really important to me when playing SC. Before SC6 I'd use Lizardman, and in SC6 the kit I personally feel most at home with would be Groh's.
As for a character I really like to play
as, I'd have to jump to an entirely different game. Under Night is my favorite fighting game. I like the base systems and the game flow, but I especially like how the characters play with the underlying system. Overall I can play a
bit of everyone in Under Night, other than Yuzuriha (I'd have to buy an entirely new keyboard just for her) and Merkava (playing him has the high cost of
breaking my keyboards).

My favorite character to use in Under Night is Londrekia. Under Night is a game that's all about resetting pressure and the name of the game is to make your pressure ambiguous since the game has a pretty extreme momentum snowball from
defensive options. Londrekia's pressure is "weak" in the sense that its full of gaps, but "strong" in that his toolkit is designed around encouraging the opponent to make mistakes. Some of his normals will completely stuff option selects and he can print plus frames at ranges that are very disadvantageous for most other characters. But the reason I like him so much is how disrespectful a lot of his unique options are. His 214X rekka can low/high crush in neutral and then be converted into safe buttons by ending with the ~A followup. He also is the only character with a 1 button air-unblockable reversal, basically an off button for most overheads and sometimes assaults depending on your reaction time (or luck).
On the other hand, I don't actually feel much from his design or character. He's voiced by Soma Saito, who has a voice I quite like, and his interactions with Merkava is kinda cute, but that's about the extent of it. He's not a cool male like Enkidu, Gordeau or Waldstein and he's not quite as much cute fujobait as Seth, Hyde or Chaos. Moreover, he's supposed to be the rival to Erika but we haven't really seen much of that so far.