There are 3 styles of hard cases, of which I have 2 (from ebay). I highly recommend the following style
This one is recognizable by the back plate. The camera and speaker have their own separate cut-outs. There are 2 different front face versions of this back cut-out. The one above has a separate cut-out for the front speaker, while the one below has no front cut-outs. By the way the camera used in the above photo is from the original MyTouch 3G.
There's also a another version with where the rear camera and speaker share one blob-shaped cut-out. The front face covers more of the bottom button area.
I own 2 of the green style (1 clear and 1 black rubberized), and I just got 1 of the red style (in white rubberized). The rubberized texture is similar to the texture of the USB cable connectors (not the cable itself) of the MyTouch USB cable that comes with the phone.
Anyway I highly recommend the red style and dont recommend the green style. The black style might be the same as the red since it has the same looking back plate, but I dont own that style. The green style came out the same week as the MyTouch 3G Slide (I stalked ebay for days as I got my phone on the June early release date). I used it for weeks and hated it. Last week I was on ebay again and found the red style so I ordered it to see if was better.
The red style is better because it clips on the left and right edges of the phone, whereas the green style clips on the corners. The left and right clip placement of the red style makes sliding the phone so much easier (almost like it has no case on it). The green style's clips (in my case the black rubberized one) requires greater force and almost makes the spring assist non-existent. The green style clips on more securely and is alittle bit thicker/chunkier (some may not like that).
I only have 2 minor complaints about the red style. Since the front face plate covers more of the screen, it peeled back part of my screen protector. After a few minutes of messing around with it, I got it fit perfectly with the screen protector. No biggie. The other complaint is that my blue jeans rubbed off onto the white case, so there are blue marks on the edges of the case. It wont rub off and I dont want to scratch it off for fear of scraping off the rubber coating. I suppose this is a problem for any light colored rubberized case. I have a white phone so I got the white case (which is flat/chalk white, not glossy).
The green style has a cut-out in the middle of the back plate to use with a belt holster. I didnt like it bacause dirt/dust got into the case through that hole, and the back plate is not flat. So the phone rocks around when you lay it down. I dont use belt holsters, so I covered the hole with a sticker.
