Python is certainly capable of combat, with enough survivability tools to make any vulture cringe in the long run. FDL is more resilient to smaller craft, lacks internal slots of the python, but has a big cannon on the front. The Anaconda, I never personally flew one, so I can't tell you. I hear a combat fit will run you close to a bil though. I would go with the FDL or the python, depending on what you want.
The Python and the FDL are maneuverable, people say they have problems against smaller craft, more typically the python because its a little bit slower, but there are ways to deal with pests using reverse and positional thrusts.