I personally would never factor side spin into my decision. I can correct clubface angle contact easier than launch angle and clubhead speed which are the leading factors as to why I need more spin/height on my iron shots. My guess is that the better players are even more height-bias as they are really good at controlling club face contact.

Totally agree I look for a good clean ball contact with a square club face that starts at my intended target and certainly cannot try to add sidespin into the equation
My guess would be try both balls and see which you are happy using

There may have been a time 12 years ago that the side spin on a Pro-V was an issue for me. I used to use the original NXT so the ball would be in the rough of my fairway. A Pro-V would be in the fairway, just not the one I was playing. It really didn’t make any difference between the X or the V.
Like Dale, my choice of the X is based on the better launch window for me than with the V. I know far to well how to generate a slice Ball choice would be more like choosing Velocity versus any tour urethane ball to try to minimize a slice.

I don't think side spin should be a fitting guideline. Because you are trying to find the best ball when you hit it square on the face... that's the performance characteristics you want, not when you mishit it.

I play the V1X because it is the right ball for me, with the right spin to hold greens on approach shots. I know I don't want a ball that spins less to keep it a bit straighter and have my ball bouncing off the back off greens on my iron shots.