I can't speak to the differences between the UC-E17 and UC-E6 cables, but since both cables are stated by the manufacturer to be compatible with your camera, they must either have the same connectors or be close enough to be interchangeable. Looking at the Nikon store pages, it seems that the UC-E17 cable may have been discontinued, which may be why some sellers are listing the UC-E6 cable as its replacement.

The UC-E6 cable has a USB Type A connector at one end and a non-standard USB UC-E6 connector at the other. Your D5200 will be compatible with any cable that has these connectors.

It is possible that the two Nikon-brand cables could have been different lengths, which might have meant one would be easier to work with than the other, but non-branded cables may be available in several lengths. All other things being equal, I would pick the cable with the shortest length that I could practically work with. (I don't like leaving my camera balancing precariously somewhere just because the cable is a little too short to place it on a more stable surface.)

(One of the cables supporting USB3 transfer rates is another possibility in theory, but while USB Type A sockets and connectors are both forwards and backwards compatible, it's unclear whether there is a USB3 version of the proprietary UC-E6 and whether it would be compatible with USB2 devices.)