Kind of depends on what your main use of the lens is going to be? I have the 70-300 VR
, my brother has the 55-300VR. The 70-300VR auto focuses much faster, has the auto-focus over ride, meaning you can grab the focus ring and manually focus the camera without having to flip off the little focus slider switch back and forth from auto to manua, and has two settings for the VR
. Normal, to allow for better panning, and Active, for when you yourself are moving a lot, like in a plane, or on a car, boat etc. The 70-300VR also has better glass, although there sure isn't anything to complain about with the quality of the 55-300. So for fast action, quicker focus, better VR
, the 70-300VR is a much better lens than the 55-300. But if you don't need those things, than you don't need that lens. The 55-300 covers a very versatile zoom range and since you already have that lens, decide what the main reason you want a different lens is....and go from there.