Game Boy Advance, especially the SP, was the greatest handheld console to me. Had rechargeable batteries that you could charge by plugging in (back in those days, as a kid, it was a game changer), played all your existing library of game boy games, amazing folding mechanism and portable, small size and of course a great library as well. Perfection. And as I say that, the Switch has proven to be an amazing challenger…
The greatest handheld console was the Genesis Nomad. Cons: - It was the size of a brick. - It was designed with oddly skewed angles. - It didn't have room for batteries inside, so they had to be shoved in a little pack that clipped on to it. Pros: - It was a handheld Sega Genesis. - You could connect it to your TV. - You could connect a second controller. - You could run it off A/C power. - Ergo it's also a console!…
Also, the screen suffers from terrible ghosting. I can barely bring myself to play sonic on it.
Still, the Nomad is a neat piece of kit.