I'd previously stuck to using Bluetooth, as it was an industry standard and things should just work. Experience with Raspberry Pis, however, showed me that they did not work as well in practice. Some keyboards would work fine but needed to be paired again on reboot, while others stayed paired like a champ but were just awful keyboards with random repeats and noisy trackpads.
So for a RetroPie box that I needed to just work, I bought an IOGEAR
RF keyboard/trackball thing. It's recognized at boot as a keyboard without drivers. It hasn't needed to be paired again. It's surprisingly okay as a keyboard for couch typing.
If you want a wired keyboard with trackpad, Adesso
make 'em. I have one on my “desktop” Raspberry Pi, and it's great. They're not cheap, as Adesso tends to sell to the retail point-of-sale market.
‘Remember the Golden Rule of Selling: “Do not resort to violence.”’ — McGlashan.