I have used most of them, starting with KAC and now run ladders. The ladders are the slimmest, dont come off unless I want em to, and dont have to slide off the front. They are also the lightestand easiest to modify for custom length. They are admittedly the weakest and are more prone to wear (consider them disposable after a year or two of rough use... keep spares), they are also the not as good if you shoot a lot of full auto since you can still feel some heat on teh metal between the slats but that is why I have a VFG.
I found my KAC rails allowed their retaining clips to rattel in my FF RAS and DD rail but not my ARM-R where they are solid. The XT never rattle, are the stickiest, but come off the easiest since there is an edge to catch. They are the second easiest to mod for length. KAC is a bitch to mod for length and requires a griding wheel on the Dremel and will cover you with a rain of hot plastic specs in all directions. Requires eyeprotection.
I didnt like any other hard panles other than KAC because they seemed slightly thicker and the KAC was already borderline too thick to me.
Any closed panel will hold up to a couple mags of full auto for fun or a few mags of crazy firing semi auto. Dont let the ability to hold up to heat be a determing factor as it is a non factor.