Cell processor shreds through whatever you throw at it. Why wouldn't you have ps3 as the lead?
The Cell is difficult to program for. It has a lot of potential power compared to processors of it's time, but extracting that power requires efforts not needed on other platforms, so developing for it specifically is often a waste of resources. Besides, general processing is not the problem, its memory and graphics (which are limited on the consoles because of cost and age, respectively). In that sense the PS3 and 360 are similar, whereas a modern high-end PC can be counted on having 4-8 times the resouces of either console, making it much easier to develop for, but making porting more difficult.
Regardless, when making a multi-platform game it's best to develop for the least-powerful platform using the lowest common features. Supporting multiple platforms is a drag on the technological advancement of many industries (though a boon to the bottom-line) and gaming is no different.