Well you can't go wrong with the OEM Samsung charging pad. Of course you'll need the wireless charging back cover for the phone if you don't already have it, and note that if you have the phone in a case of some sort it probably won't fit any more with the wireless back as it's just a tad thicker than the standard one.
I've been looking at this option myself for my S5, but the potential nuisance of having to mess with different cases means I probably won't bother.