I've had 2 Optima batteries... one that came with a car I bought and one I got from Optima because I won a race they were sponsoring... actually I've had 6 Optima batteries because both went bad twice before I gave up on Optima batteries... not before I nearly burned my garage down trying to charge one with a regular charger.
If you put a battery in the trunk, there is value to using an AGM, but if its still under the hood, Walmart all the way.
For AGM I would go Bosch before Optima.
I have the Cteck 7002 charger for the AMG battery, it's not fast but it works well. As far as the Wallmart batteries the Everstart does have the agm battery.