
Exped
MegaMat Series
Car camping comfort king; warm and durable.

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Depends on what type of camping. If you are car camping and space is not a concern, your most comfortable option is an inflatable mattress. Cots are somewhat more comfortable than pads, but not as much as you would think. My current favorite is an extra wide/long klymit style inflatable. I think they are more comfortable than the backpacking cots by themselves.
Ahh ok then yea low or no R-value would be fine in those cases. Klymit also makes a good lightweight low R-value pad, it's what I used in Texas and worked quite well in warmer weather. Not as heavy or thick as the one you linked, but much lighter and packs down smaller. Great if you're backpacking but there are better options if car camping imo. Exped Ultra 1R is also a good pad, the more insulated 3 and 5 are also popular for colder temps. I've used the Dura versions which are a heavier/more insulated version and it was comfortable. I've also heard good things about Nemo Tensor but have no experience with it.
Same, I use uninsulated for trips that get well into the 40s. Great weight-cost-comfort ratio. I will never carry the insulated one again though. Way too heavy for that overinflated R value. Fine for car camping.
I went this exact route also. But just with an uninsulated static V for 2 years. OP if you're on a if you're on a strict budget, the regular static V is $90 at Canadian Tire, $80 on Altitude Sports (online only, out of quebec, but they are reputable and I use them often). If you have some flexibility, Altitude Sports has the static V insulated for $127 right now. If you camp primarily between June and early September, the regular static is all you need. Insulated would be much more comfortable outside of that range, but I did find the static to be fine in colder conditions as long as an appropriate bag was used. They way they're designed lets the bag stay a little bit loftier under you, as opposed to a flat pad that fully compresses your bag under you. Do not get the static V lightweight if you're worried about leakage. It's a much thinner material on top than the regular statics and I believe the dimensions are a tad smaller.
My neo air is noticably more comfortable than my static V, but neither of them is as comfortable as my bed at home, which in turn is not as comfortable as my hammock. I'm usually tired enough when backpacking to make it through the night on the neo air, but I try my best to camp somewhere with trees, so I can hang instead.
Stacking generally works in really simple formulas. Using (2) R-2 pads stacked will get you about an R4 insulation, which would be great for this situation. I don’t know if you’re driving or backpacking or what, but you might consider an inflatable pad paired with your current pad. It’ll pack smaller, should be more comfortable, and since you don’t really need a high Rvalue air pad it wouldn’t need to be a huge budget investment. I generally don’t recommend pads from brands like Klymit due to their lower R values, but something like a Static V paired with the foam pad should be warm enough for above freezing and would be more comfortable and more packable.

Exped
MegaMat Series
Car camping comfort king; warm and durable.

NEMO
Tensor Series
Lightweight side sleeper favorite, but polarizing on warmth and noise.

Exped
Ultra Series
Comfortable, quiet side sleeper pad; compact for backpacking.

Big Agnes
Rapide SL Insulated Sleeping Pad
Comfortable with unique side rails; R-value and durability disputed.

Therm-a-Rest
NeoLoft™ Sleeping Pad
Very comfortable; a bit 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