Depends on the campaign - if I'm in it for the long haul, I prefer a High Elf Fighter/Magic-User. At low levels, a Dwarf (or, if possible, Half-Ogre) Fighter is lots of fun, because you're relied on by the rest of the party and role-playing ideas come very easily through play. Medium levels, I like Thieves, due to the creative thinking and role-playing opportunities; high level, gotta go with the Human MU.
