(Longer LK1) Difference in gcode really creating that much of a difference?

I've been running some prints, some of them the only real difference being the gcode flavor set for the printer. The default was Marlin, I think the manual for the printer is telling me RepRap should be the selection, and the other type I've tried is Ultimaker 2. Marlin and RepRap, for the most part, have left me with weak results, as if not enough filament was extruding the entire time. Ultimaker 2 has been the complete opposite- the prints I've done have been EXTREMELY sturdy, everything filled, however, it got so extrude-happy that it left filament trails every time it ever had to leap, enough to make the result unsatisfactory. What can I do to find a balance in all this?