I'm a huge fan of seidio spring holsters but no word yet on a release date. Ive tried the verizon leather horizontal case and its ok but I ended up exchanging it for the oem holster and screen protector. I text a lot so a holster is perfect cause I can just pop the phone out a lot faster. Seems to hold it in very well too.
I bought a hard case w/ holster from the verizon store. It is called Shell/Holster Combo. This was the thinnest case they had. I wanted a thinner case because I was having issues on reaching the top row of keys on the slide out keyboard on my friends droid (he was using a rubberized case). I have no problem hitting any of the keys with the case on. After three days of use I have to say the case is pretty nice for these reasons:
-Dirt/crumbs don't get in it
-small lip prevents things from coming in contact from screen EDIT: such as countertops when in your pocket, does not prevent usability in any way
-easy to remove
-thin yet protective
One noticeable flaw in the case is that it covers a portion of the speaker on the back, but doesn't muffle the sound really. I can't really comment on the holster portion, because I don't use it.
I had the VZW hard silicon case, liked the way it felt, but it would not stay on the back, and I didn't like that it covered up the buttons, and it did make the phone feel a little bulky. I am now using the shell/holster combo. Much lighter, less bulky, stays on and doesn't cover the buttons. It does make the phone feel less secure than the silicon cover, as it feels more slippery, but I can now clip it to my belt, which is a plus. Still searching for the perfect cover. A nice combo of the two would be perfect.