In intellect I would rank the espada as the following.
1. Szayel(overated I know)
2.Barragan( ex. god-king of hueco mundo must know something)
3. Ulquiorra( good analysist and make percise judgement)
4. Aaroniero( I'll be happy to make a semi-long explanation if needed)
5. Halibel( seems to be a causious person but lets emotion cloud logic)
6. Stark( The primera appeared to be like Kyouroku but not that much)
7. Nnoitra( A complete douce but taking out a weaken lion-Ichigo/Neliel-
is a pretty good hunting strategy)
8.Grimmjow(I might be undermining him but oh well
9.Zommari( Pretty darn stupid telling someone your whole power set)
10. Yammy( A total retard that was all bark and no bite)
That's about it.
I agree with you on the ranking, except for Grimmjow and Nnoitra. I think those two should be switched. Grimmjow has been shown to be quite the analyst when he correctly deduced that Ichigo could only fire about two or three more getsuga tenshos during their first fight. from what I remember of Nnoitra, he doesn't do anything like that. true, he had a pretty good hunting strategy, but it doesn't make him particularly stand out.
I know Stark's wolves are powerful but I really think that Barragan really should have been the primera. This might not be the question asked but here's how I would rank the espada.(including the second release)
1.Barragan
2.Ulquiorra
3.Stark
4.Grimmjow
5.Halibel
6.Nnoitra
7.Zommari
8.Szayel
9.Aaroniero
10.Yammy
I know there already ranked and set but based on feats and performance, here's how I see the espada. As for Grimmjow and Halibel, even though she wins sympathy points for being killed by fanservice she still didn't live up to the title of #3 like Grimmjow lived up to the title #6. That's it
Man that was a long post.