How you like to play and fitting your play style is the most important. Choose what is best for you. That said, I have two turreted size 3 beam lasers on top and a single gimbaled size 2 multi cannon on the bottom. Because I'm currently mining, the other two top slots are filled with size 2 mining lasers. While mining with my python, I can get attacked by 1 or 2 small AI ships and don't even need to move out of drone range. I just spin or tilt and let the lasers do their thing. If attacked by something with a bit more bite, manuvering is a must to avoid too much pressure on the shields, but usually find the lasers have reduced their shield to nothing. Then I line the multi cannon up and finish them off.