Does your DM tell you your foes' hp?
Maximize, IMHO, is better for sorcerers than for wizards, but I'm still not fond of it all that much. It depends too greatly on knowing the odds, and players in D&D don't generally have that much information about same.
As far as average damage goes, a Maximized fireball (60 hp) inflicts only 7.5 hp damage, or less than 15%, more than an Empowered fireball (52.5 hp). Is that worth the extra spell level? I'd rather prepare all my fireballs Silent and Empowered than Maximized.