I vote for wizard.
And for HP? I stole something from the Starship trooper RPG (d20 style), Where everyone begins with their constitution in hp and gets 1 or 2 extra points each level. What I did was to give everyone their constitution+a bonus from their class at 1st level, and then a half the 1st level bonus+their constitution modifier after that. So a 1st level barbarian and a 1st level wizard both with 10 constitution get 20 and 12 respectively. The bonuses went like this: Barbarian 10/5, fighter/paladin/ranger/defender 8/4, cleric/druid/monk 6/3, bard/thief 4/2, and wizards/sorcerers/warlocks/wizard variants 2/1. So a 20th level wizard with 10 con has 10+2+19hp (31 hp), while a 20th level barbarian with 10 con has 10+10+95hp (115hp), while a fighter with 10 con has 10+8+76hp (94hp), a cleric with 10 con has 10+6+57hp (73hp), and the thief with 10 con has 10+4+38hp (52 hp). This means that the meat shields have a nice large amount of hp that scales quickly, while wizards have a low amount at all levels. Looking at this I might go back and change the numbers to be slightly higher for thieves, bards and primary arcane spellcasters, so they can survive more at high levels (need a way to make the defender good at defending, maybe a 5th level ability that lets him taunt as a free action).
Edit: the sorcerers spells per day look a bit weird at the high levels, is that spells per encounter the roll?