Air Bed for me, I think most people over inflate them hence the dislike by some I do use a sim as well and as others have said don't over inflate it makes them uncomfortable
10cm Outwell Dreamcatcher and camp bed for me, although I probably wouldn't bother with the campbed if it wasn't for having dodgy knees and find it hard to get up from the floor first thing. Other advantage of a campbed is lots of storage space beneath it. I just got a cheap one from GO. My partner says the best and most comfy sleeping arrangement he has tried is one of those camp-beds made for fishing with adjustable head rests. I think they are usually padded already and you can make them into loungers. They're wider than standard ones as well.
Try SIM's on the floor to start with then if you feel you need a bit more comfort get camp beds and put the SIM's on top.
We started on 5cm SIM's on the floor which were fine (even for me at 17 stone) but with the advancing years (and subsequent aches and pains) we splashed out on a double Outwell Posadas this year and put the SIM on top, never had such a good nights sleep in a tent as we have with the Posadas!
------------- May 2015 - Arrow Bank 4 nights
July 2015 - Manorafon 4 nights
August 2015 - Piccadilly Caravan park 3 nights
August 2015 - Wheal Rodney 11 nights
If you sleep fine on the floor, then a SIM would appear to be the perfect compromise. We have the Vango Comfort double, which is 10cm thick. It is quite bulky when packed but it suits us both very well; I am prone to sciatica, and my partner has Parkinson's, so we have specific needs for a firm but supportive bed. With a big rug that extends out on either side, we can make a very cosy nest with square footed sleeping bags.
we have just got back and we have used an airbed we got from aldi earlier in the year and it was great so comfy it was unbelievable, the only problem was the size it wouldn't fit in the inner tent of our annex on the awning, I am 6ft 4 and had loads of room even with the mrs spread out