RU6 is a very good recommendation, so is the Lotoo, I have the S1 and I like it. I had Helm Bolt and liked it the best but sold it and I think I should not have!
My recommendation though goes to the Fiio BTR5, I do not like a dongle sticking out from the phone, it gets a bit cumbersome. The Fiio does Bluetooth and USB both and SQ on Bluetooth is really nice, it is tiny enough to be tucked away in your back pocket and out of the way.