With this question in mind (the first one that stackexchange is offering me right now among the "Questions with similar titles"), I'd like to steal the idea of the question and ask it about PPC.
What's so great about it? All other chips I've seen - ARM, MIPS, SuperH, x86 - crunch numbers just fine.
The background of this question - about PPC, that is - is that the PPC architecture is used in many DSP chips, in particular in the automotive industry. Of course, this could simply be a question of momentum, and allow the developers to stay with an architecture they know well, including the toolchain. And the software they've written until now, of course.
But assuming I'm starting a DSP project anew, without any old baggage to lug around - is there any compelling advantage of the PPC architecture that would persuade me to prefer PPC to, say, ARM?
Knowing about the power efficiency of ARM chips, let me mention that my design would run off the grid, not on batteries.