I cannot decide on the ideal build.

[SolEiji]

The Problem: Create a summoner with a side of enchantment and fries.  Specifically with Summon Monster.  3.5 and Pathfinder available.

The Puzzle: The PF Summoner seems like the winner, but the lack of enchantment is a problem.  I could go with a sorcerer.  Or a wizard.  Or a cleric.  Or maybe something else.  But I really can't decide what is best.  With no base to start with my optimization-fu is worthless!  From where should a summoner/enchanter begin?

(Bonus points if the summoner is capable in defense too.  Offense matters less.)

(EDIT: It also occurs to me that I did not post this in MinMax as intended.  If someone would be so kind to move it...)
(EDIT: Arigato,  Agita.)

[Agita]

Moved as requested.

Have you considered Wizard into Malconvoker (Complete Scoundrel)? That's the first thing I think of when I hear summoning with enchantment. Since Pathfinder sources are open, Greater Eldritch Heritage (Abyssal) and Superior Summoning would let you pull all kinds of shenanigans with sheer number of monsters summoned. What starting level are you looking at, anyway?

[SolEiji]

"Under 10".  It's likely high, so like 8 at least, but I don't want it to be too high.  Yeah, we'll go with 8-10.

I totally forgot about Malconvoker.  I'd think it might be fitting for me to alter it to a law-chaos aspect for this particular build's fluff.

(Eldritch Bloodline wouldn't help, the relevent summoning ability, DR/good, isn't granted via those feats.)

[Calico]

The relevant ability Greater Eldritch Heritage would be getting you is the Abyssal Bloodline's 15th level ability which reads as follows:

Added Summonings (Su): At 15th level, whenever you summon a creature with the demon subtype or the fiendish template using a summon monster spell, you summon one additional creature of the same kind.

I don't know how well it meshes with whatever law-chaos thing you have in mind, but it dovetails quite nicely with malconvoker.

Also from pathfinder would be the kitsune favored class bonus for sorcerers which provides +1/4 to the DC of enchantment spells.

[awaken_D_M_golem]

Erudite 7 Discipline Metacreativity ... for Conj crossover
learn piles of spells, ditch the psicrystal for Magic Mantle(d)
Nar Demonbinder 1 into Mind Mage and Cerebremancer
to deal with the erudite prc hinkyness,
psiotheurgist after Nar ... and just use lots of telepathy stuff
not quite as borked diplomancing and Dominate at level 10+.

Not Tier 1, but very good conj use.
Recharge if you can't resist.
 

[SolEiji]

I was recently introduced to the concept of a binder summoner, via a web vestige.  It's interesting and provides infinite ammo, but not much versatility in what I can use.  Presumably there's at least one vestige available to fulfill the "enchantment" part.  Is it viable for the idea?  And is it compatible with Malconvoker?  Or does the pseudonatural summons strip away fiendish/celestial templates?

[Agita]

That would be Zceryll, from... that one web enhancement about Binders in FR. She allows you to use Summon Monster at will to summon pseudonatural creatures. Since she gives access to the whole line, has other powers, and you can bind another vestige at level 8 too, it's feasible, though she's incompatible with Malconvoker.

[JohnnyMayHymn]

have you seen this?  the binder option gives you an insane number of options... once every 5 rounds(not at will)

"You can summon any creature from the summon monster list that a sorcerer of your level could summon.... -this"

Hrm, so are we not 'casting' summon monster 3, we're just summoning a monster from the list?.

Hrmmmm, I don't see any duration listed either, or that you have control of the monsters that you summon....

[Endarire]

What about a Gray Elf Generalist Wizard/Malconvoker/Incantatrix or such?

If you're using Pathfinder's school banning rules, and you want to specialize, consider Gray Elf Wizard (Conjurer - oppose Divination and one other, such as Necromancy) as a base.  Remember, spells Pathfinder's opposed schools require 2 spell slots to cast, which can be tolerable if you're using them only on off days, like for animate dead.

[ZombieGirl]

As an alternative, you could always go with a greenbound summoning archivist, you'd have access to SNA, CIB and SM, along with all the goodies of all divine casters (including divine bard). You'd also be able to pursue DMM for some additional shenanigans.

[vaz]

Enchanter variant Wizard 20? You pick up Summon Monster anyway, and gain Social Skills, and free Extend 11/day works well if going for low power. Ban Necromancy and Evocation - if you need some Necromancy doing, summon or Bind something capable of doing so, and Evocation, well, Summoning something else does it better as well.

Alternatively, Wu Jen, optimizing its Spirit Binding line, and tacking on Mindbender.