
Exped
MegaMat Series
Car camping comfort champ, but some side sleepers find it thin.

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I'm a sometimes side sleeper and for some reason I'm totally fine on anything more than a CCF pad. I honestly find a 1.5" SI pad to be the most comfortable for me including when I'm side sleeping.
I use a thermarest trail scout because it's what I have but the thermarest prolite is a bit lighter and the women's version is currently on sale on Backcountry.
it depends on what r-value you need, but honestly most sleeping pads that are thick and comfortable are going to be inflatable of some sort, either self inflating or otherwise. under a hundred you'll end up with a zlite or some other foam pad which is fine, but not very plush. I use an old thermarest (maybe a scout?) on a neno switchback and it's pretty comfy, serves me down to about 25°f. when my partner and I go camping, we use an exped megamat which is great. we have friends who use a Nemo roamer and they love it.
I'm a larger guy and I use the Thermarest Trail Scout Pro. It's decent though I have thought about an upgrade. One thing I do like is my hammock in the summer. Maybe worth checking out
It's honestly just a 2003 regular grade thermarest judging by the ones I've seen as surplus here in Anchorage. Non ridgerest closed cell foam was the budget answer (and the only answer for a long time) and still works as great insulation in the cold for small money. Just information for your decision matrix - you gotta carry it all!
Thermareat Scout and REI Air Rail Plus both going on 5 years with several weeks and many weekends every year using them.
Your options are going to be closed cell foam (basically a yoga mat), open cell foam (often called self-inflating), or an air mattress. Closed cell foam like a nemo switchback or thermrest ridgerest are simple, bulletproof, lightweight, warm, and cheap. But they don’t pack down terribly small and aren’t the comfiest. Air pads are the new and fancy systems. You’ll want to be careful with R value when you’re picking these. You’ll need a higher R value for colder weather trips. Klymit static V isn’t a great pad, but it is cheap. Sea to summit ether lite is an awesome pad, but not so cheap. Air pads are small, much comfier, but can get punctured and have to be inflated every night. Open cell pads like thermarests trail scout or base camp are going to fall into the middle of the pack. Comfortwise, pricewise, sizewise, etc. they have all the problems of air pads and are heavier. But they’re cheaper and often warmer. Sea to summit, therm a rest, big agnes, nemo, and exped are some of the big names in the sleeping pad game.

Exped
MegaMat Series
Car camping comfort champ, but some side sleepers find it thin.

Exped
Ultra Series
Lightweight side-sleeper comfort, but a bit pricey and bulky.

NEMO
Tensor Series
Ultralight side-sleeper comfort, but slippery and prone to leaks.

Big Agnes
Rapide SL Insulated Sleeping Pad
Comfortable with side rails, but heavy and warmth claims disputed.

Therm-a-Rest
NeoLoft™ Sleeping Pad
Very comfortable, good service, but heavy and bulky for backpacking.

Ranked #1
Exped - MegaMat Series

Ranked #1
Exped - MegaMat Series

Ranked #1
Exped - MegaMat Series

Ranked #1
Exped - MegaMat Series

Ranked #1
Therm-a-Rest - NeoAir Xtherm Series