The 70-200 is an absolutely superb lens. Its contrast, sharpness, and resolution will all beat the 70-300 99% of the time. It has a constant f/4 aperture, great build quality, and no extension when it zooms or focuses. It white in color, which attracts a lot of attention, both from thieves and other shutterbugs.
The 70-300 reaches 100mm further, but gives up some image quality in the process. It's a touch slower, but IS makes up for that if you're capturing a relatively still scene. The 70-300 @ 200mm has a max aperture of f/5.0, which is 2/3 of a stop slower than f/4. It's a more inconspicuous color (black), which may be a plus for you.
It basically boils down to whether or not you need the extra 100mm of reach, need the IS, or want a lens that won't attract a lot of attention.
The 70-300 reaches 100mm further, but gives up some image quality in the process. It's a touch slower, but IS makes up for that if you're capturing a relatively still scene. The 70-300 @ 200mm has a max aperture of f/5.0, which is 2/3 of a stop slower than f/4. It's a more inconspicuous color (black), which may be a plus for you.
It basically boils down to whether or not you need the extra 100mm of reach, need the IS, or want a lens that won't attract a lot of attention.