Marine Tex and Devcon seem to be the most popular ones to use for bedding. I've read many, many posts about JB Weld, and haven't seen anything describing issues with it. Having bedded a couple rifles with JB Weld, and a couple with Devcon, I can say that Devcon is harder when it dries, and is more abrasion resistant.
I have also repaired an aluminum AR lower that I totally screwed up by partially refilling the fire control pocket and re-machining it. The epoxy bonded well to the aluminum, but it has not been put to the test yet (I just assembled it last week). My expectation is that it will do well, but time will tell.
I say all that to say this: as long as you get a good bond between the aluminum and the epoxy (whichever epoxy you choose), I think it will do well. To get a good mechanical bond, rough up the surface of the aluminum with heavy grit sandpaper, maybe even drill holes in it, then clean it very well with the something like acetone (be careful using it around plastic stocks, as it can destroy certain plastics).
Good luck!