Plain old superglue works pretty well if you make sure the surface is spotless (I give the board a quick light sand followed by a clean with turps or similar prior to sticking on.) It's not totally fool proof but usually lasts me 6 months at the very least. I have tried a 2-pack araldite way back when, but it only lasted a few months and left THE WORST residue on the board which was a nightmare to get off in order to stick the pad section back on.
I've been using Aquaseal for re-glueing the stock gripped back to the board. Cleaned the area thoroughly with turps first though. seems to work well. Otherwise as mentioned above, for glueing a whole deck pad on I'd say contact adhesive would work well too.
I've used the gorilla glue that activates with water and that has worked pretty well. It doesn't seem to leave gross reside either if you decide to ever peel it off later.
A friend used contact cement and that worked well also.