I think the right tool it depends on the type of projects you are doing. For designa and strategy projects where you need to see the versioning of documents and want to track comments/feedback in line, basecamp is still the best. The new basecamp looks great too. I dont like basecamp for scheduling, task management, tradition project planning.
For agile projects, or projects that are very task based, I love Pivotal Tracker or PM Robot. PM Robot is great because it as a unique set of "client" permission, a feature not present and Basecamp and Pivotal. I think Pivotal's user experience is the best, far better than Jira and Fogbugz, which I used for years but will never go back to. Pivotal and PM Robot are great because it easily allows clients to (drag and drop) prioritization of tasks.
I think the best hybrid btwn basecamp and Pivotal/Jira-type tools is Wrike. Wrike is great for schedule and shows and nice gantt chart. And is task oriented.
At the end the day you need people to adopt the tool and use it. So look for the tool that has the best user experience. They all share 80% of the same functionality.