AGM or Lead-Acid?

I put an AGM Vintage style "MOPAR" Group 27, Red Cap, Turbo-Start in my 70 Cuda in 2013. Never disconnect it but I keep a quality battery maintainer on it over the winter or if I know I'm not going to drive it for a while.
I bought the Battery in late 2012 and put it into service January of 2013.
She still cranks like new every time. My typical running voltage is 14.4V-14.5V... "¯\_(ツ)_/¯"