Totally depends what you're trying to accomplish. Basecamp can be great for managing a whole project in all its complexity. But often times that's overkill, and too many features get in the way.

We[0] differentiate by keeping it as simple as possible: have discussions and make decisions together, that's it.

Other tools are great for other types of projects, such as Trello[1] for a sort of collaborative to-do list.

[0] http://www.loomio.org [1] http://www.trello.com