My preference is ProV1x, which I switched to last year from the ProV1 as I was looking for a lower trajectory.
I love the feel of the ProV's around the green. I have a shag bag full of old ProV's. Started with about 50 that I bought on eBay and throw more in when they get too scuffed to play with.
Balls are one area I won't skimp. For those who only play them on "special" rounds, how can you stay consistent if you're not always playing the same ball?