Well, my main problem is that I have used Prismas exclusively for so long that I don't even know what the other brands feel like. People swear by one brand or another or another, and I wanted to see for myself what's good, bad, and weird about the different ones that I can get ahold of here in the States.
My Canon scanner dulls down color too, to some degree; I generally spike the saturation in Photoshop to bring back the eye-searing brightness that I so enjoy.
I'm not very fond of the Crayolas, myself. Though I've seen a few pros do amazing things with them, I don't get good blending out of them. The wax tends to build up on me and make the textures all gummy.
The granules of stuff in Prismas don't happen all that often, and there are a couple of specific colors that it seems to happen to more frequently than others (one of the light blues and a couple of them in the red-violet family, mostly), so it may have something to do with the specific composition of those colors, or a big, bad batch of lead that proliferated over several thousand sets over several years. Hard to say.
I'm familiar with a bunch of different brands, based on what I see in the Dick Blick catalogue and at Jerry's Art-a-Rama - both catalogues sell the same brands most of the time. I've tried Prismacolor Premiers, Prismacolor Verithin (their hard-leaded line), Lyra Rembrandt, Faber-Castell Polychromos, and Aquarelle watercolor pencils. I have a couple of old sets of Spectracolors made by Berol quite a few years ago; don't think they're available any longer. I have some Carne de Arche, Derwent Coloursoft, Blick Studio, and Irojiten types that I've not used very much yet, but plan to in some upcoming experimental projects. Most of these guys are soft-leaded types, except for the Polychromos, as I wanted pencils that I could compare against the Prismacolors that are most familiar to me.