There is a bit more flexibility in the rules than what you seem to be using here. I would say that, as long as the spell is not uncastable (lawful clerics can't cast [chaotic] spells, etc) and the creature is suitable to the task, each deity would have more than one option.
So, for instance:
LG: Archons (LG), Angels (any G), Guardinals (NG), elementals

or inevitables (LN)
NG: Archons (LG), Angels (any G), Guardinals (NG), elementals

, Eladrin (CG)
CG: Angels (Any G), Guardinals (NG), elementals

, Eladrin (CG), Slaadi (CN)
LN: Angels (LG only), Archons (LG), Inevitables (LN), Formians (LN), Devils (LE), elementals
LE: Inevitables, formians, devils, elementals, yugoloths
Etc.
I also would say that the allies should be given in accord with the deity and the task to be assigned. So, for instance, in Greyhawk, a LG cleric of Heironeous who cast Greater Planar Ally to get an ally to help track down an oathbreaker might well get an inevitable. That's their job, after all. If he wanted a guardian for a group of refugees, he might get a Guardinal. If he just wanted someone to move a pile of dirt from one side to another or to build a castle, he might get elementals. If we were discussing a LN cleric of Bralm (godess of insects, order, and industry), the cleric might get a devil if he was summoning something to punish his enemies, and formians for ordinary work.
In the Forgotten Realms, a CN cleric of Shevarash (CN god of vengeance and hating the drow), might get a Vrock or an Eladrin depending upon the task. Shevarash will use any instrument for his purposes (exterminating the drow) regardless of their moral compass.
On the other hand, a core rules St. Cuthbert (as distinguished from the Greyhawk St. Cuthbert who is LG), despite being LN would probably not ever be served by devils.