Summon Familiar Alternative Class Feature

[tedcahill2]

What's the best alternative class feature for Summon Familiar for a Mystic Theurge?

Alternatively, what's the best familiar for a Mystic Theurge?

[ExLibrisMortis]

Umm, Immediate Magic on a conjurer?

There are a whole lot of ACFs, you can also go for Rapid Summoning, or one of the Dragon ACFs (348, 357, quite a lot of the later ones have ACFs for some class or another).

[Elkad]

The best Familiar is one you trade away and then buy back with Obtain Familiar, so it keeps leveling up with you.

At low level, Hawk (spot - his +16, not the +5 he gives you), Owl (almost as much spot in partial light, and massive move silently), Rat (fort saves), and the ever traditional Raven (speech, possible UMD) are near the top of the core choices.
Hummingbirds or that dino for Initiative are also nice once you wander afield.

If you want to spend the (second) feat on Improved, there are a bunch of great choices, though you have alignment restrictions to worry about.
Coure Eladrin
Pseudodragon (has 5' reach for landing touch spells)
Imp (and the slightly-weaker Quasit)
Musteval Guardinal
Beguiler (True Sight!)