I've long been using UIFX, mostly for novelty's sake, but now that I think about it, Mamesick was continually adding new ui elements in line with new MAME features. Hell UI doesn't even have a tick box for HLSL - let alone GLSL stuff, etc, etc......
But as far as a gui, UI still serves. Game folders and lists drop right in and display (I think this is why I've panned EmuLoader, let alone QMC: I want the same display experience as UI). And especially as I don't do MESS, I don't need more than cabinets, marquees, titles, and cpanel at the right.