As a current student, the only major differences in colleges is the accommodation types. The whole college associations don't really stand for anything.
Each college has their own sports/bar team and each college will organise trips to places or nights out (currently Fylde and Bowland are going on a trip together to Leeds tomorrow).
My advice: pick the accommodation you want first, then pick the location of the college. If you want central colleges on campus, definitely go for Bowland, Furness or Fylde. Grizedale and Pendle are slightly more out of the way but not enough to feel a difference. Lonsdale, Cartmel and County are a bit more of a trek across campus if you need to get to a building on the other side. (I highly recommend checking out a map of the campus before you make your choice).
Finally, it's worth mentioning:
- if it will bother you, there's an in-joke that depending on your type of accommodation you are either in the 'posh' part or the 'ghetto' part. This literally is just a joke about whether you have an en-suite or a standard room, there isn't anything more to it.
- if you're worried about the college bar you'll get, it doesn't matter. You can go to any bar at any point no matter what college you are.
- if you want inter-competition between colleges, apart from Grad college, each college has a rival.
To conclude:
1) pick base on accommodation type
2) choose the most central colleges which have this room type
3) don't get your hopes up you will get that college anyway.
- I didn't get my first or second choice of college but I'm happy in the one I've got because it's still central on campus.
Any more questions just fire away and I'll be happy to help.