I going to base my least-liked simply on play time, and going by that it's:
Least - Minsc! I get him just too late. Magic items have already been optimized, pairing combinations gelled, stories developed. Maybe in a play through I'll beeline to him Act3 before even Rivington.
2nd Least - Halsin. Act2, it's over. Sex pesting when MC is well into a relationship is not welcome. Plus he competes with Jaheira, who's actually a top 5 favourite. Guess I could respec him.
3rd Least - Karlach. On release I thought she'd be top romance pick, but found her simply unattractive. Doesn't help I prefer fighters over barbarians, and she's not very barbaric anyway.
Honourable mention - Minthara. Locked behind evil (for romance) or neutral path. I'd quite like her as a companion, but for me massacring the grove requires a certain MC with leaps of logic.
