Right now I have some Wilson iWounds that I am trying to play through, they're left over from last year when I got them on clearance. Usually play Nike SuperSofts.
Wilson Pro staff (The really expensive ones)
Callaway Warbirds in my bag (Not too expensive)
Dunlop (Cheap)
Ill tee off with my callaway and if the round go well i will upgrade to my wilsons and if its poor then i will downgrade to my dunlops. More often than not i dongrade because I cant keep buying expensive balls.
Last couple of rounds I have played with NXT Tour. I think I have only about 3 or 4 balls in my bag. I guess I concentrate better knowing I only have a little ammo in my bag :)
I only play Callaway Balls and I alway have 15 balls in my bag.
I use the Titleist NXT Tour. It's good with my clubhead speed, gives me good distance off the tee, good control with long irons and exceptional greenside performance. I usually carry three in the ball carrier that hooks to my bag, one extra sleeve for me (just in case) and one extra sleeve for whomever didn't bring enough. If I'm golfing with my son I bring two sleeves more because he never saw a water hazard he didn't like.
ProV1's, usually 10 or so in the bag. When I find other balls on the course I'll either leave them or give them to a playing partner, unless it's one I feel like trying out.