Late to the party too, just found out the game some weeks ago.
I couldn't pick a single favourite, since it depends on the character game run I'm doing (old time RPGer, I tend to build a char and stick with what he/she/he-she would do/prefer), but certain characters always get their way on my personal preferences (too many it seems
)
Like:
--Urta: love her. She's clearly meant to be a main char, so I always end up doing her. She has a wide arrange of options, so no matter the character I'm running, it'll fit the concept. Shy, cheeky, dominant, passive, straight, fetish, cute, obnoxius, take, give... always entertaining.
--Helia: love her. She's an adorable slut. Fits the role of the active girl that doesn't gives a fuck about what others think (or actually, she does lol). She fits most of my character builds. (and I'm biased because she reminds me of an old gf I had, including big boobs, red hair, and boozing out)
--Izma: love her. The "powerful warrior that submits" gets me every time. Again, his options fit most of my chars: kids for my breeding bitch female warrior, dominant fuck for my submissive herm mage, and all-around great fuck for my hunked up male warrior (love the fact I can be aggressive even when she's going alpha). ((she's also a good template to make other characters, specifically one I have in mind)).
--Cotton: like her a lot. My only gripe is that she has few sex options, and one is replaced for another one (service her -> tantric sex) which is basically the same than his first.
--Loppe: like her a lot. But in the end she gets maybe a bit repetitive, and doesn't feels like I'm achieving or advancing anything, and the texts are somewhat long.
--Lottie: Like her a lot. She's the exact description (on e-v-e-r-y aspect) of an old GF, so I'm biased. Pity there aren't most sex options.
--Amily: like her. She's more suited for caring/loving characters, tho I don't find her attractive for aggressive male chars.
--Arian: like him. Didn't pay attention to him at first, since lizards aren't my coup of tea, but recently started to build him up with a female, and he's pretty interesting (sort of a male Amily).
Don't like:
--Kiha: annoying and whinny. She's a decent fight, but doesn't fits any of my tastes for characters types. She's not dominant, slutty, motherly, or passive enough. I guess I could just keep her as a friend, but doesn't have interesting things to talk neither. What's worst, I don't even have a clue what's with all the "B-Baka" stuff, since I'm not keen on hentai-manga stuff (which I guess that's all about). And I have Ember for the mattter, which is a lot more interesting even when she's not complete.
--Scylla: complicated, and restricting. The descriptions are way too long, and it's focused on breast-inflating, something that doesn't really gets me (actually, it's the descriptions themselves that I find uninteresting). Not being sexable as a choice, it also tends to pop up right when I'm trying to do something else on Tel'Adre.
Sorry, for the long text (something I complain on the game lol)