Hawk52: Viconia's a good cleric solution. It honestly makes no sense that she's evil in-game. She appeals for help due to being persecuted, she
politely requests to join you, and one of her messages when you kick her out is "You've been so nice to me, and have shown me that not all surface dwellers are bad." Hardly evil actions.
Luckily, she automatically lowers your rep by two when you pick her up, so if you're at 19 or so, you can keep her around as long as you avoid doing any goody goody actions afterwards.
MikeMaximus: She was my first choice and I agree about her alignment, it's nice in BG2 that you can get her to change alignments (if I remember correctly, it's been years). But for this game I decided to get rid of her to keep to the "good" party i'm trying to role play. She certainly wasn't that polite to me when i removed her, nor her comments when she started complaining. She said something about me being surface scum and returning to the underdark. In fact every single npc i've dropped from the party has said something horrible to me.. :D
Probably due to your reputation. I think I was about 11-ish when I got rid of her. Honestly, unless you're only taking good characters, it's kind of annoying to play super high reputation. Neutral or Evil will constantly whine and complain which gets really, really grating after awhile.
Sadly, you can "game" the reputation system really easily in BG1 (you might in BG2 but I can't remember). Kill a neutral random "townsperson" without being seen and get an instant -10 to reputation with no repercussions. Then you can raise it back up by donating to temples. It really undermines the system when you can easily corrupt it.