was thinking about getting the nvidia shield, wondering if emulators are optimised for android tv? By that I mean I can play with a controller, easily select through the menus, and it won't have the onscreen controls for android phones?
I seen people using retroarch but I'm not really a big fan of launching all consoles from one app. Would rather dedicated apps for each, specifically nintendo and sega consoles. Will this be a problem?
You can do what you're saying with most emulators. Retroarch and the .emu emulators are the most popular.
Also don't underestimate the convenience of Retroarch. For most systems the cores are excellent, and you get a very cohesive experience with robust features. If you use a frontend you don't have to see the GUI either.