I got a
Sena case recently, and have been very happy with it. It does not have a belt loop, it uses an UltraClip from The Clip Company. It's a very strong clip, locks the device in very well. I haven't had a single problem with it slipping, coming loose or sliding off yet.
The case itself is a snap closure flip cover with cutouts for access to all the buttons and cards (even the reset button has a cutout). I'm very satisfied with this case so far. It might be worth your time to take a look at the website.