You should look into a Palm Stikine. The zipper is on the back, like the IR, which is much more comfortable then one that goes over your should like a kokatat. They are totally dry and one of the toughest suits made in my opinion. My buddy hot a kokatat GMER at the same time that I got my Palm, and my suit definitely held up better then his (and almost every time we went kayaking, we went kayaking together).
I used me Palm Stikine for about 125 river days and it stay totally dry until I slid 50 yards down a scree field on my butt. The fall caused me to put a pin hole in the suit, so I sent it back to Palm to see if they could fix. THE DRYSUIT WAS NOT UNDER WARRANTY. They said no problem, and had me send it to them to have it fixed. A week later they called and let me know that they did not think the drysuit was holding up to their standards, and that they were going to send me a BRAND NEW one fore FREE!
It's worth getting a Palm for their customer service alone.
No Questions about it, Palm or Kokatat is the way to go and I doubt anyone will dispute that.