As another poster pointed out, the environment we're talking about in the survival situation is going to matter a lot.
Cody Lundin lives in the Northern Arizona desert apart from anything he's done on camera in Dual Survivor, and that expertise shows a lot in the desert episodes of DS. Lundin is the hands down top desert pick. Les Stoud, on the other hand, has to cut his stay in Kalahari Desert short.....but he did OK in the desert in Arizona.
Les Stoud, on the other hand, went and lived for a year with his then wife in Wabakimi Provincial Park at some lake named Goldsborough Lake. That's a forest environment, so Stroud is going to be the best at forest survival hands down.
Bear Grylls has done a ton of stuff involving climbing/hiking around mountains, so I think he'd be good is that type of environment. That said, unlike Lundin and Stroud, we really just don't know for sure how he'd do on his own because he never lived it alone.
Dave Canterbury, Lundin's cohost, did a lot of hunting and stuff in Florida.....I'm not convinced he'd be great in swamps though. If he's going to be his best, though, it's going to be in an Everglade's type of environment. That said, I'm not convinced he'd be the best option even there.....we just don't know for sure.
Regarding environments with snow (not just snow but that arctic type environment), I wouldn't want any of them, or the guy Mykel Hawke from Man Woman Wild either (he had to get emergency assistance in Alaska....also had to get assistance in the desert fyi).
None of them are total experts in jungle either, but Lundin and Canterbury both go on and on about how they don't know that much whenever they're there... Hawke and Grylls seem to know a good amount in them and do a great job. Stroud does too and had one episode where he learns knowledge from some tribe living in the Amazon itself.
Overall, Stroud is probably the most rounded, but probably not the top pick for at least one or two environments (and none are ideal for the snow/arctic).