Re: Which P90's?
Of the different P-90s I've used, I have come to the opinion that regular Gibson P-90 is the best. Not too hot, not too weak, and they have that classic growl, fatness and bite.
As Aceman said, live with it for a while before swapping it out. If it's really not floating your boat and you want something hotter, both the Hot and Custom Duncans are good. The Antiquities are nice too - I like the neck version (paired with the Gibson in the bridge). The Ant. bridge was missing a little something to me - maybe it's the Alnico 2?.
I've never played the Dimarzios or other brands so I can't comment - although I've heard that both the Fralins and Lollars are excellent.