Of course, there is at least one person I've encountered that did both. He installed a Hand-All on his Glock 21 then wrapped the A-Grip around the frame and Hand-All.
Personally, I have come to dislike the Hand-All as it gets slick with continued use. Moreover, the palm swells are not quite in the proper place at least for my hand.
The A-Grip is interesting, but heaven forbid that you ever need to detail strip the frame after you apply it. In spite of the advertising claims, once you remove it after a long installation, it will not stick back in place again.
If forced to use a 'Glock-sock', I would go with the Uncle Mike's unit. However, I tend not to use the sleeves anymore in preference to a bare frame or the application of skateboard tape.
Walther has advertised an interesting slip-on unit called the Derma-Grip. It looks like a standard slip-on sleeve crossed with skateboard tape. From the picture, it also appears to have a shrink-wrap quality. (The uninstalled sleeve appears much larger the the installed version.) This seems plausible as the old MasterGrip sleeves were designed to shrink in place after the application of heat from say a hair dryer.