I see a lot of love for some of the high tech ships as solo-combatants, but I haven't found anything better than a Sunder. In this configuration, I can fight just about anything while retaining awesome mobility. It's the same 2x AM cannon and 1x autopulse that people are using on the apogee in a faster, cheaper to operate package.
By activating the high energy focus and firing the AM blasters, you can drop most ships shields in a single blow. If they don't overload, they get close enough that by opening up with a fully charged autopulse you can finish their shields and deal some heavy damage, and usually finish them off if needed with the harpoons. I haven't fought capitals with it yet, but I can take on any cruiser with relative ease by repeating this procedure a couple of times. The Vulcan cannon is hands down my favorite PD in the game, and the coverage provides great defense against missiles and light fighters. Heavier fighters can be addressed with the autopulse.
By picking off fighters, circling around to destroy carriers, and then destroying everything else one at a time by hitting fast and hard, retreating to dump flux, and repeating is great. You can set the ship up like this at a low level, and add extra hull mods and vents as you level up tech (my preferred skill tree).