I would suggest 1/2elven F/M/T for your solo class, decent melee, spells, and thievery, slightly better hp than a T/M. I've had alot of fun with my Duo (picked up Viccy for the romance).

with either elven chain or Vecna's robe you'll be doing fine on AC and still casting spells, and in BG1 you can switch armor out during combat. Another option is the Tutu mod which gives BG1 the BG2 interface including kits so you could solo through as a monk or barbarian.

Go with the Sorcerer! ;)

The problem with Sorcerer is that it basically counteracts the point of Tactics since people who are not that tactically proficient, and are playing solo sorcerer (like me first time around, although it was my first BG2 game in general actually) tend to resort to summoning 50 planetars in every battle.