Assuming this question is serious (and not an attempt to start a flame war) then I can think of 2 answers.
The first applies if I was doing a personal project in which case I would chose the one that had the more memory and peripherals and not be too worried about a few pennies/cents/<insert your favourite currency here>. Also I'd lean towards whichever device was supported by the development environment I had the most familiarity with.
The second applies in a commercial environment where I would be looking for the device with the least memory that satisfied my requirements and had the least number of unused peripherals but still had the best footprint for automatic PCB placement and the lowest unit cost. (In this case I would probably not be looking at the 100-off price but for the higher quantity breaks.)
In short, it all depends on your circumstances and requirements.
Susan