Personally, I'm for Acraglas. I buy the "shop kit" which is 28oz of resin, and 7oz hardener. About 6 years into my knifemaking career, I learned about "epoxies" the hard way. Prior to that I had used mostly Devcon "2-ton", and just assumed it would be good forever.
I started getting calls from clients who were saying "The handle on my knife is coming loose." I ended up rehandling a number of knives, but not before I did some serious research on "epoxy"..... long story short, I learned that the majority of 2-part epoxies are engineered to only last 5-7 years....then they chemically break down. At first I found that appauling, but after a phone conversatioin with a chemist for "one" of the epoxy producers, who told me.... "My job depends on this company selling epoxy.....I'm certainly not going to engineer an expoxy that lasts forever!" ... I suppose if you look at from that point of view, it makes sense.
Where longevity is concerned, nothing tops Acraglas.... 10 year shelf life, and guarunteed 50 year hold life. Next in line is West Systems Marine epoxy, with a 5 year shelf life, and a 30 year hold life. I did some testing on my own, and found that with proper prep, I could "glue" a hidden tang handle on with Acraglas, and once cured, I could bust the handle material with a hammer, but the "wad" of acraglas would still be on the tang. I could chip it with a cold chisel, but couldn't break it off with a hammer. That, and the hold life has caused me to stay with acraglas ever since. I suspect sooner or later something "better" will come along, but I've not seen it yet.
I was a "tester" for West systems G-flex, personally I did not like it. Its too thick for use on hidden tangs, and on full tangs it always left a small, visible "glue line", which varied based on the type/color of handle material.
In the end, I suspect that had I not had those "loose handle" incidents, I probably would have never thought twice about the "glue" I was using, but I view it as a blessing in disguise, in that its likely saved me a lot of heartache through the years.