I think the only Mages that I've never tried without a Spawnpoint are Druid ('cause Treebond->Vine Tree), Necromancer ('cause both are amazing, and I always swarm with him; the tough decision is which Spawnpoint to go with), Anvil Throne Warlord and Forcemaster ('cause [mwcard=MW1J04]Battle Forge[/mwcard] is the most versatile Spawnpoint in the game, and I have yet to try a pure "caster" Forcemaster using several Mind's Eyes). Actually, I can't remember if I've ever played Priestess without Temple of Asyra... but that's mainly because I rarely play Priestess. I've definitely tried Gate to Voltari (Mana Worm swarm), Pentagram (mainly in Domination, but at least once in Arena), Barracks (both Arena and Domination), Lair (duh), etc.
I've tried all 3 of the Paladin's Spawnpoint options and haven't decided which is best. Probably Battle Forge, but then he plays a lot like Anvil Throne Warlord, and I don't like having so many books that all play the same way.
The only Mage I've never played with a Spawnpoint is Siren, as I find Echo of the Depths really pricey and generally prefer Naiya (who is a Familiar, not a Spawnpoint). I guess it isn't terrible, but it has a difficult time getting +1 Channeling (which is Pentagram's problem) and is easily destroyed (e.g. it just takes a Dissolve or Crumble, and unlike Libro, it doesn't have a Cantrip-like ability)... although it does have something analogous to Enchanter's Wardstone (or Armor Ward) going for it.