I would get the MS290, if you are limited to spending $350. They have some pro features, like 3/8 b&c and an adjustable oiler. But like Cereal Killer says, your hands will be numb compared to using an MS361 or a PS-5100s vibration dampened saw. The 5100s will cost you more like $400 though, if you can find one. A lot more saw for the money though.
I would stay away from the MS250, as they are smaller, more plastic, no adjustable oiler, and they do not run full size chain. They are also a PITA to work on. They are good for small trees and limbing. An MS290 will fell large trees and I see a lot of pros use them all the time (loggers, tree butchers, and county workers). You can also easilly modify the muffler and richen up the H screw in the carb, and it will have 10% more power. Easiest saw to mod that I have done.
I have owned and run all of these saws for years, except the 5100s. I am Windthrown, and I approved this message posting on AS.