Well, I've had a few different bags in my years of playing. Currently on my Kolstein is a standard Mooradian that I need to replace one day. Protection is OK, but the side handle came loose and the zipper is broken near the bottom. Despite that, I like the fact that that it folds down small and has a slippery texture. The reason I say that is my Standard has the Messina bag that I got from Andy at ISB this summer. It has the afore mentioned tough exterior but also has kind of a rough interior as well. I bought it for the Kolstein, a small 7/8 and the bag is for a large 3/4. It's a tight fit, which I like, but the rough interior was rubbing off the Kolstein's varnish on the edges. Not too cool. But on the Am. Standard, it's filling the bill fine for the bus trips(has a bunk)and I like the extra handles in the center for loading/unloading, extra pockets, and the sideways pocket in the back for music.
For a short while I had the ProTec bag. It was very stiff and protective as it's name implies, but would not fold down at all and added a lot of weight. That went with a bass I sold when I bought the Kolstein.
Recently, I heard Mooradian will repair it's bags for no cost, so I will probably try that avenue since I have an extra bag on hand. The next bag I'll probably get would be the Deluxe model, since it has extra padding and still folds down very well.