There are two differentiating features that Sysomos MAP has that the competitor tools I have experienced (Radian6, Meltwater Buzz) did not: user-friendly Boolean queries for searches and near-real-time results. The former is important because, of course, your results are only as good as your search/campaign. With Sysomos, once you master Boolean queries (which isn't terribly difficult) you're set for creating any kind of listening report. I strongly prefer this to the "campaign creator" forms that other services provide.
Second, Sysomos MAP returns results almost immediately - like a Google search. So if you get your results and see that you need to tweak your query - no big deal. Or if you have a last-minute request for a client - not an issue. Meltwater can take up to 48 hours for a search to fully populate. This is a major issue if you get your full set of results back and see that you need to adjust the query; you're looking at another two days of wait time. A long wait on results can also prove problematic in agency settings where clients or prospective clients often need results with a quick turnaround.