I've used (owned) number of them and here's my feedback:
Stofens (or omnibounces) that comes w/ the flash are relatively decent. They aren't the best out there but for the price, their versatility is really good.
Fong: I have the clear and cloud ones 1st biggest difference b/n the two is the color balance. But in a small room where you're from your subject at any given point LESS then 10 feet, I very much like the fong - either shooting direct flash direction or vertically up.
Demb Flip it: another great tool. Similar uses as the fong. Except I find with that I can shoot at distances of 15-20 feet and not put out as much power as I'd need to with the fong to get the same results.
The good thing about those 3 is that they
look like real gear and not DIY. Problem that I've seen was that number of clients when see something funny (i.e. tissue paper) they begin to question one's professionalism

Nonetheless, with tissue paper from the local arts&crafts store that only cost me a $1.00, I got some similar results that my colleagues got from brand-name bounce cards - ONLY difference was the LQQK.
Left hand, that was cute,
yet true. When I'm using bare flash and/or stofen and need to shoot vertical quick shot, It is my left hand that I use as the bounce card - I'm just amazed how well it works :lmao:. The only down side is that the camera,grip,flash,lens are all in the right hand and THAT is a lot of weight, at least for me.
Bouncing of the walls, ceilings, shirts, etc: I do when going for some
specific effect and more often then not VERY pleased with the results. The downside is not always is the color of the wall is the color I'd like my image to be.
Few years ago, I was in similar situation where I asked my colleagues, friends, tpf members as to what is better and why. Then answer I received was similar I got after experimenting with various modifiers: they all have their optimal situations and they all have their downside.
Good Luck w/ you search.