Most people nowadays suggest using their phones. High end phones in the last few years are so powerful they can emulate up to PS2/Wii/3ds and everything below. That being said not all like a controller like this one.

But going that path you want something simple a lot of people look up Powkiddy like this unit. You should browse their site as there are different ones with different power and form factors. All should be sold on Amazon or eBay.

I'm using this one on my ZF3. No lag that I have noticed outside of typical xCloud hiccups.