I've been using acra glass for almost 40 years too. There are several things I know about it that makes it a simple decision for me.
1) I've never heard of acra glass changing with time. Especially shelf life. Never have to wonder.
2) You can control viscosity and set time with temperature. Handy.
3) No waste. I've been using the same plain old syringes to measure exactly as much epoxy as needed for a couple years. Squirt it into a dixie cup and mix with a popsicle stick with a slightly angled end. Simple and clean.
4) Brownells sells atomized aluminum and stainless steel to make the epoxy stronger. Works great as a thickening agent. Takes on some properties of the metal, including visual properties, to a degree. I don't know why it's never spoken of. I use it often.
Of course you can use any other type of thickening agent. I collect some dust of whatever I'm sanding to thicken and/or tint the epoxy for near invisible repairs.
5) Has it's own aerosol release (anti-stick) agent which has no effect on the epoxy. Works better than you'd imagine.
6) Has it's own thinner. You can thin one cc or one quart of epoxy to the consistency of water without affecting the strength of the epoxy. Super easy clean-up, again without affecting the epoxy.
7) Easy to tint any color. Take small syringes to the paint store. Pull the plunger out and let the guy squirt the tint into the tube. One cc of a few colors of regular paint tint will tint gallons of acra glass.