I've tried from 2.5 inch inflatable BA insulated pads, to GG NigthLight egg crate pads, to 3/8" closed cell foam pads, to 1/4" GG ThinLight pads. What I have determined, at least for me (YMMV), is that site selection is what really matters. If I sleep on hard desert floor on a 2.5" inflatable pad, I won't sleep any better than on the 1/4" foam pad (which won't be very well). All the pad does for me is #1 insulate me from the cold ground and #2 make the sharp objects I'm sleeping on less uncomfortable.
So as the ultralight maniac I am, nothing is substantially better than the lightest option, so I go with the 1/4" foam pad for my 3 season gear. I simply chose to sleep on top of some type of natural padding/insulation, and I sleep great on my super thin pad.