I think it depends on you and your personality. By dating a lot of people for a short amount of time, you are definately broadening your horizons and scoping out different kinds of people, figuring out which you get a long with more. But you don't get to fully know the people that you date. By being in a few longer relationships you get to know the people you date, and you are showing that you can be committed to a relationship for a long time, however, it shows that you could easily be thinking that every relationship you enter, that they are "the one". It depends on the person really. There are positives and negatives to either.