USB devices generally give more resolution options, but introduce a 2-5 second delay between what you're doing in the game, and when its displayed in OBS. If you don't mind that delay, then a USB device is just as useful as an internal card.
Of course there is always the USB3.0 devices like x-capture 1 that don't have a delay, but that costs ALOT.
As far as internal cards go, you don't have a great deal of options other than a Blackmagic Intensity Pro, or an Avermedia Live Gamer HD