I can give you my opinion because I have all three. Leader Grips were fine, but I almost immediately upgraded to Red Snappers which I still use. I don't remember why I did that.
I usually pin the top of the back and I use the Red Snappers on the bottom of the back. I do this because I have a Liberty with a 20 inch throat and some of my quilts are fairly big. If I use Red Snappers sometimes the tube gets in a position just right to take up ½ inch or so of my throat space and I have trouble getting the needle to the other edge if I'm using my CL boards. I hope that makes sense, anyway, I float my tops.
I had (and still have) several sets of zippers and hated them from day one. It was way more work than pinning or using the Red Snappers. The zippers are nice if you have to remove the quilt in the middle of quilting it in order to put another quilt on. I don't sew for others so that was never an issue.