I personally think Brigands are more compelling in raids and Swashbucklers are more compelling in groups... both offer a strong presence in both and neither can be said to be anything but strong in each environment. I think Sage sums it up well. Brigand burst damage is being toned down just a wee bit in LU24 and I think it will make this distinction very slightly more pronounced.
If you decide Brigand makesure you like a backtabbing playstyle. I do as it happens which is why I chose Brigand in the first place, as it keeps me engage as a player during combat. Again this isn't a huge distinction just something to keep in mind. For instance when looking at the STA AA line as a Brigand I'm aware of the fact that all my best CAs will be difficult to use if tanking.
I personally group a lot more than raid and I'm considering switching to Swashbuckler. If I raided more I'd definately stick as a Brigand.... and to be clear I'd repeat that's not to suggest that both Rogues aren't strong in both raids and groups.