You may want to consider building the MBHP as this appears to be the one most people (?) are now building and therefore has the most support, new firmware & Development.
There are really only two things to consider when buying the PIC:
Get a 20MHz, i.e. ..F877-20/P instead of -04/P
Get a DIP40, that is one that is socketable instead of SMD (surface mount) variants.
The letters mostly stand for which temperature ranges the PIC can withstand (for military applications, for instance), so the cheapest one will surely do (or do you regularly control Pro-52 while on your weekly arctic expedition?)…