I think as the game expands, the Shadowheart romance will become the most rewarding to follow. There's not much to it now, but it could have some great Cold War Spy Novel story yet to come.
Gale is the one I'd be warning my friends off in real life. He's got controlling partner written all over him. Proper warning lights popping for him. Sweet and charming when it's going his way, but there's a nasty edge to him when you deny him, and his reactions to the PC romancing Asterion are very telling.
I also think that Lae'zel wouldn't romance a non-Gith. Use for sex, yes - and possiblty that's all she'd use a Gith for too. But when Kith'rak Voss calls the rest of the party slaves, I don't think she sees us any differently.
I don't think about Wyll for romancing any of my characters, but I am looking forward to watching the Wyll/Mizora thing play out. I'd prefer to get the option to steer that relationship into break-up or make-up with or without the Pact.
Astarion gets all the best lines, and the Vampire story is a classic. In Early Access, he's my favourite but with a fuller game he may lose out to Shadowheart.
I tend to play the hell out of games, so I'll of course play all the options in EA and release before playing my "personal canon run" whoever that may be with.
Edit: I did just realise, there's no option here in BG3 that I would reject as hard as I did Anomen in BG2.
