I've used the Big Agnes Q-Core (regular and SL), the Exped downmat 7, and several neoairs. BA comes in at the tail of the pack: heavier than it needs to be, not as warm as its weight calls for, and least comfortable of the three. (Bear in mind: comfort is purely a personal call; there is no objective way to measure it. Like others said, you have to decide this one by trying them out in the store; we can't make a call for you.)

The Expeds are incredibly warm and very comfortable (but not as comfortable, to me, as the NeoAir. Again: emphasis on "to me.") However, I don't need that much R value because I don't camp on frozen ground or in subzero temperatures.

I've pretty much settled on the NeoAir as my pad of choice, and my favorite is the 66" All-Season. It hits just the right combination, for me, of warmth (R4.9), weight (18 ounces), and comfort (I like rectangular pads as I can "sprawl" a bit, and I've got a corner to rest my hand on.) Yes, it's more expensive than the Trekker; whether it's worth it is a call you have to make for yourself. I've also used the "women's" Neoair Xlite, also a 66" pad, and like it except for the tapered shape. (The only difference I've found between it and the men's/unisex version is that for the same weight, the R value is about 20% higher. Call me Sue.)

The 66" pads are, for me, essentially full-length. I'm only 5-10, and my shoulders are placed at the top of the pad; my pillow uses my pack as a base, so my head isn't even on or over the pad, and doesn't need to be. Also, I'm a side sleeper, and tend to bend my knees slightly. So, 66" is plenty long, and it leaves me a little more room in the tent to store other gear.

You might also want to take a look at the Sea to Summit pads. They're thinner, but provide substantial comfort (second only to Neoair, in my opinion) at about the same weight. (A 1.5 inch pad versus a 2.5 inch pad effectively adds an inch of headroom to your tent, which is nice, too.) I've spent about 15 minutes on one of the prototype Ultralight models, and it was nice, but not nice enough to get me to switch. I have a buddy who used one of the Comfortlight prototypes on a 10-day JMT through hike, and absolutely loved it.

For me, NeoAir All Season does everything I want a pad to do, and does it just right.