[Qwinn]

The methodology that Towerwizard suggested is what you do if your intent is to get maximum hit points. At level 10, fighters and clerics don't get a full hit die, while thieves and mages do. Therefore, if hit points is your primary concern, taking thief at 10th level theoretically gets you the most.

Shameless self-plug: I do have to note that none of this silliness is necessary with my mods. My Fixpack changes the way hit dice are gained to match what it says in the manual: you gain hit points as a fighter when you raise your highest level class regardless of which class it is (and none when levelling your lower level classes - you weren't supposed to get that 1hp then either).

Qwinn