I have tried tons of the backpacking style air pads and I think they all suck. I wanted to side sleep without feeling the ground at all, have enough insulation that I can cold camp.. and just generally not feel like im falling off the sides or be to short (im 6'2").
They are a bit large, but I have Alps Mountaineering Comfort Series Self inflating air pads. I have the XL 3" thick and XXL 4" thick. I think the 3" is probably plenty, but they are very comfy. I'm not sure a cot would be more comfy because these have some give
blocks dust mites, but you don't feel like you are on an air matress as much (they aren't mostly air, they feel MORE foamy than most). They give just the right amount.
Hugely subjective and hard to say how different people will feel about them... but ya. Only downside is they are a little large packed which is a bit of an issue.. space is tight.