My personal favorites to keep in the bag are a glow beadless aviar and a wizard.
The glow aviar is nice and soft, kind of like a JK, but its more understable because it is beadless. The nice thing about it is that it holds a straight line longer than a big bead does. That means more range! On a hot day though, it can be a little too soft. The Wizard is a great overstable putter. Its kind of like a cross between a big bead aviar and an XD. Its shallower than an aviar which allows it to come out of the hand easier, but it still has the bead which keeps it overstable. Its good for hyzer putts, and can be used a lot like a roc from further out. I think its a good substitute for a roc if the roc doesn't feel right in the hand for you like it doesn't for many. It also makes a great forehand roller for those times when you need to get around a bush or some trees and you can't go straight through. From my experience though, you get good with whatever you practice with so find something that feels good in the hand and learn to work with its flight pattern.