big and white is the only way to fly IMPO
I think this is all getting a bit partisan, and for no good reason...
I'm guessing that most of us have our favourite tools, a beauty dish is certainly one of my favourites, but it's far from perfect for every subject and every shooting situation. As I've said before, it's hard on skin blemishes, and in fact using a silver one is a bit like using a magnifying glass on the skin...
So, if you're a fashion photographer who knows just how far he can push the contrast, if the model slept in her own bed last night and if you have a good MUA then the silver one is a pretty obvious choice. If not, then the white one is more forgiving but less dramatic.
What I personally like about beauty dishes is that they're a bit of a combination tool - very crisp light that's also fairly soft, or can be depending on position, a very sharp cut off of the light itself, and variable shadow transition, depending on distance. Stick a honeycomb grid on it and it becomes a different tool again. Stick a diffuser on (without the honeycomb) and it becomes a softbox. Use both a honeycomb and a diffuser and it becomes a very crisp tool, which adds highlights to the hair (as well as where you don't want them) but with softer edges.
Up to a point, you can get broadly similar results with other tools, but they just ain't the same - a softbox for example is a pretty versatile tool but it can't produce really crisp light with the front diffuser on, and can't produce even light without it. A fresnel spot is another favourite of mine, but they are all pretty small and because of this the shadow transition edges have to be pretty abrupt (the best one I've personally used is the Bron, But it was enormous, overpriced and lost a lot of power with the iris closed up, but it was the best simply because it was about 14" diameter). The Lencarta one is 9" diameter and I like it a lot. Pretty well everything else I've tried is too small for people use.
There's a lot of truth in the saying that if the only tool you have is a hammer, every problem looks like a nail. You actually have to have a lot of experience of a wide range of tools to form a useful opinion on what works and what doesn't.