If you're just gonna have windows or small files on it, i guess a lot of usb 3 drives could do it. The windows installer copies all the files over and uncompress afterwards, so its only accessing the drive when thats happening, and when you boot from it. A read speed of 100mb/s or 150mb/s is not going to change much then.

I have the Kingston datatraveler R3.0, generation 1, it is solid, some years old now though. And its not that expensive.

don't forget you cannot install Windows from a USB 3.0 drive

Wut? Why not? It works just fine and there is even a way to make Windows 8 (and I presume, 10) portable on a USB stick/drive.

Some mobos have issues booting from USB drives though (and there might be glitches with USB 3 controllers) but that's not a windows specific issue.