Strictly speaking, a straight Batman wizard is better than an Ultimate Magus--which has to jump through a lot of hoops to get 9th level spells. If you are really bent on being on being an Ultimate Magus, then go Conjurer or Focused Conjurer/Beguiler/Ultimate Magus. That way you have only one casting attribute. Prohibit Illusion, Enchantment, and (if Focused) Necromancy on the Wizard side. The Beguiler spell list makes up for the Illusion and Enchantment loss but, at least IMHO, the Contingency spell is a lot more useful in the long run than the Necromancy school.

Mercs aren't cheap, especially for the long haul; did you see the prices?
But you wouldn't really need them. Cleric and Druid can, in a pinch, handle melee all by themselves--especially with a Batman wizard and an Artificer backing them up.

Of course, if you really want to power game, go gestalt.
Cleric//Paladin: the Ultimate Holy Warrior
Wizard//Archivist: The Ultimate Batman
Sorcerer//Favored Soul: The True Mystic Theurge
Druid//Ranger: Nature's Ultimate Defender
Artificer//Factotum: The Ultimate Skillmonkey