Can someone tell me the difference between these dry suits and which one is the best?

You probably dont want SAR suit for casual fishing.

I would go with kokatat instead.

https://kokatat.com/mens

I use Hydrus 3 dry top with Hydrus 3 whirlpool bib. If you look long enough you can find them on sale for around $500 for a set. Its not goretex but close enough. I use bib only as waders. Top and bib as a set for dry paddling. Easier to put on than a full suit. Never had issue with leaks between bib and top when properly married. Proper undergarment and you can be warm and safe in cold weather. Kokatat offers lifetime warranty and also pretty much they can fix anything on your suit for a fair price if needed.

/r/kayakfishing Thread