Conor Maynard's cover is probably the best overall arrangement and vocal mix we've come across. The the huanting vocals to the solid beat breaks this is one cover that doesn't disappoint. Check out his page here.
You've probably seen Devvon Terrell on a few other covers. He's quickly emerging as a good to artist for quality covers and overall good music. On this cover he's joined by the all girl singing group, The Janes. Check them out on this cover and let us know what you think.
Jamieboy's cover does a great job of adding vocals and ad libs like you'd expect an RnB song to sound like. Check him out here: Jamieboy
vChenay's cover keeps the beat with a smooth breakdown that allows you to hear the warmth in her voice. Great arrangement on the music with vocals that actually keep the feel of the song. Visit her web page to see what else she has going on.