I have really been loving my steam deck lately. I've now played through Fallout 3, New Vegas, all of their respective DLCs, and am about 100hrs into 4 right now.
Normally I play indie games since that's where my interests are and I grow tired of the AAA jackassery.
I mention that to illustrate that I do use and live the deck. But I guess I'm not creative enough to use the back buttons at all. So to the title question:
What games do you play that make the most use of the back buttons?
In games where combat uses the bumpers a lot I bind the back buttons to that. For the rest of the games it depends on the what I find annoying to do repeatedly and end up mapping that to a back paddle.
For example on Breath of the Wild the back paddle was run which allowed me to run with one hand.
I'm trying that on FO4 right now. Instead of clicking in left stick, I mapped it to R4. Seems more natural than holding down the click on stick that you're also using to move directionally.