Looking for a phone controller.

I have a Galaxy S7 and I want a controller to make playing games on it more enjoyable. Hopefully something that won't conflict with the otter box case I got with it.

I play an emulator for Pokemon Emerald which I think I can keybind with a controller and I was thinking of getting Minecraft pocket edition which I would hope would work with one as well.

What do you recommend? Most of the ones on Amazon seem to have kinda poor reviews.