The party cleric just hit 11th level, and can now cast "Planar Ally" - if she has time, what are some good outsiders she would be able to summon?
The list seems to be considerably shorter than the demons & devils the bad guys can summon... the Angels are too powerful (min of 14 HD) and there are only two Devas in the Fiend Folio, and not much else that I can find?
There's the TRUMPET ARCHON, AVORAL, COUATL, GHAELE, LEONAL, LILLEND, Noble Djinn.
Possibly an Inevitable ZELEKHUT.
Don't forget that with PA, you aren't limited to stock creatures off out of the MM. You can use it to summon unique and/or advanced/templated versions of creatures. Templated creatures are in your favor since they increase the CR, but not the HD of a creature. But this sort of thing is something you'll need to discuss with your DM.
Also depending on the morality/attitude of the cleric, keep in mind that unlike "summoned" creatures, anything called with PA actually DIES if killed. This is probably most relevant if your DM permits you to call "custom" entities.
Don't forget, just because they are good and work for the same god, doesn't mean their motivations and desires are the same as your's or necessarily in your interests.
Also don't forget about Elementals. They don't really start coming into their own until you get SM VII (huge elementals). But from that point onward, they are easily one of the best things you can summon (huge HP, good attacks, plenty of damage, special abilities, resistances).