Honestly? Just their basic tacos. Maybe the Doritos version if they still have those. But just get a couple of the hard tacos with some Fire sauce. If you like those, you may like other things on the menu; if you don’t, you probably won’t like any of it. They’re Taco Bell distilled.
Just tried it, with a GBA Castlevania game (of course) and it handles beautifully. If this the future of AppStore allowed emulation, I’m a fan.