Either way, both options aren't very good.
I've been in situations where both happened.
But, I guess for me, a good friend that moves away is worse because we still wanted our friendship to go on but had no choice to say goodbye. Even though there's technology that keeps us in constant contact, it doesn't beat going to the bar together and checking out the scene. Basically, doing things in person.
Losing touch with a good friend who lives near by happens quite a lot to me. We grow, we want different things and experiences. I do believe different people will give you a different exposure to different instances.
Also, if the both of you live quite near and no one takes the effort to keep in touch, it seems like both parties don't care enough to continue the friendship. Both sides are to blame.
If it's one sided and your friend keeps blowing you off, pick up your pride and be friends with someone that would cherish your friendship, not just have you around because they have no one else at the time.
If you keep blowing your friend off, well, you should know what's coming for you when your friend moves on to other people.