For a couple years I've been using an REI 2.5" "self inflating" mat. Note the quotes - it's anything but self inflating. It also roles up huge and takes up a lot of room, but was fairly comfortable once you winded yourself trying to get it firm. (extra fun at elevation!)
I decided I wanted something more compact to store and looked hard at the Exped Synmat with their built-in hand pump but 2 problems came up- first, although the hand pump works it takes longer than I'd like and 2nd, they're too wide to fit in the sleeve of my lighter Big Agnes 15* bag that calls for a 20" wide pad.
I was intrigued by the speed valve mats from Thermarest, but they don't yet have an insulated one and since my BA bags all rely on the pad for bottom insulation (and I sleep cold) I ruled them out. They also seemed loud and crinkly when I gave them a test-run.
I ended up going with a Sea to Summit Comfort Plus Insulated 'mummy' shape. It's actually a little over-size at the shoulders being 21.5w, but it still fits the BA bag well enough. It's a dual-layer, so you can make the bottom as firm as possible for side sleepers (I toss and turn so much I pretty well hit everything) and still adjust the top layer to suit. R5 as well, so that helps with the cold.
I just placed the order this week so I haven't put it to the test in the field yet but from playing with it in the store + very positive reviews I think it's the best choice for me.
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I should mention it has flat valves that deflate super fast and let you inflate it fast as well. I picked up a exped 'schnozle' and about 1.5 pumps gets it ready to go. I was really sick of messing with those crappy old round valves that don't have a check in them - trying to blow them up by holding your tongue over the valve between breaths gets old real fast, and they don't deflate very well either. No love for those things!
