If only it was that simple... Basic data says ProV1x spins more and gives you higher launch that ProV1. Clubhead speed, handicap, and driver carry should not be your sole indicators on what you need. Are you already a high ball hitter? Do you have issues with wedge backspin or too much release? Is feel more important to you than spin? Everyone has different needs and desires so you have to make the choice that best suits what you are wanting to achieve. My suggestion is to either get a formal fitting or at least do a side-by-side comparison on the course. Play a ProV1 and ProV1x on every shot during a round (when time permits and I'm not playing behind you :)). Go with what gives you the best results for most of your needs. Then stick with it a while to get comfortable. Good luck out there.

To add to Dale's accurate comment, any serious golfer should play the same ball to know how it reacts to various shots. Without regard to brand, the premium balls are designed to be more controlled through spin around greens and for consistent flight with all clubs. Simple fact, urethane premium golf balls provide the best performance. Posting here with a 3 handicap, you should consider the Pro-V1, -V1x, and AVX. Which one can be determined on course, but some time with a track man (i.e. Titleist ball fitting) can validate the user experience or narrow the choice. Titleist provides quality 2 piece non-urethane balls, but there are compromises with the performance compared to the 3 & 4 piece premium balls. To note, Dale and I both used Pro-V1, but with further testing this year, he moved to the X and I moved to the AVX. Different strokes by different folks.

Take one of each and go to the putting green, whichever one feels better with the putter is the one you should pick. The X will feel firmer, fly a shade higher, spin a bit more.

it depends on how you want the ball to fly and react to the green. I'd suggest buy those sleeve of balls to try them out.