Who conjures monsters better?

Since, I asked questions about the animist v. witch for summoning, it came up that the witch ends up having better support till we get an apparition with summoning spells. I thought we might want to open up the list to different classes.

Which would be better at the summoning job, a Druid, Cleric, Wizard, Witch, or Summoner? Of course this is considering the changes from Impossible Magic, which seems to alleviate the spell slot issue with Summoners.

Summoner:
Has more feat support, and could be built in a few ways to provide a lot of action compression, or mounted to stay away while using the minions for their benefits with the action compression. Hell, its in the name.

Wizard:
Wizard: Spell blending for more level equivalent summons. Arcane only...which isn't much of a hindrance but does control some choices.

Note on Spell Blending: I do think people are exaggerating the need for more high level spell slots. Your summon should last at least 3 rounds unless blasted down by a boss, but then he did that instead of doing the same to your party.

Witch:
Sustain Support, Cackle, all in all great, and can choose Occult, Primal, Divine, or Arcane.

Cleric:
Support magic, buffs, more defense than the squishy witch and wizard.

Druid:
A tiny bit of class support, animal companions, some feats, primal magic only but they are all good.