AGA-T2 and RSST are both very good devices in general.
Main difference is, the RSST is made for ease of use. With insulated contact points and spring/ washer at the center post, its gotta be the easiest RBA to set up. No hotspot problem, no wire spitting etc.
The AGA-T2, on the other hand, is like most other RBAs. You got uninsulated wick hole, and some screwing action at the center post. It has a steep learning curve, but once you learn it, no Genesis RBA is ever gonna give you trouble.
I think of it like learning to ride a bike. You got a kiddie bike with a pair of training wheels, and you got an adult bike. When i was 10 i jumped on a real adult bike and learned how to ride a bike. I find it a better way to learn.