College grove is less modern than MB, has all the international students (which could be good or bad depending on your fondness of foreign things!! must say though most of my mates aren't from the UK!!), is 2minutes walk from the lecture theatre, close to the museum (essential for revision of dissection!!) however has less people overall (100 compared to a few hundred in MB, therefore more people you might get on with!!!), MB has a common tv area which is pathetically small but essential throughout this years ashes (even though I didnt live there), also has more parties (simply because there are more people!!).
Anyway theres a quick summary, also in CG you only pay £15 for internet whereas a basic internet package from MB is £7.99 a week, I think, might be month, not too clued in, tis expensive though!! Wherever you stay you'll make mates, more important is probably what societies you join and your tutor group.