The ED version is so much more expensive that it must not be worth it. The "G" version must be worth $150 as long as it works and gets you shots from long distance (which it will).

The differences you'll experience will not likely be in the sharpness of the lens (well, not a HUGE difference), but in the amount of chromatic abberation (CA), flare, and distortion you get from the lens. However, I'd think that CA and flare will be the biggest differences between the G lens and the other 2 expensive versions, while the difference between the ED and VR versions of the lens isn't in photo quality at all --- it's just the VR.
Oh, and you really can't shoot landscapes with a 70-300 mm lens. It's not nearly wide enough. Maybe if you want to shoot nature, maybe some leaves, small animals, etc.
ALL these lenses are slow. Yes, VR is useful because it makes the lens somewhat hand-holdable. However, it isn't worth its price for me, personally. What if the subject you want to photograph is moving? Your slow lens with VR is still going to produce soft pics. If you're shooting animals in a forest or sports in dark-lit stadiums, this will matter. Otherwise, ignore what I just said.
I haven't checked the American prices (which are usually the best), but it's likely still expensive for what it is.... a lens that can go to 300 mm with f/5.6 aperture. If I were in the market for a Nikon telephoto, I'd try to find a used 80-200 mm f/2.8. It's a fast lens, will give you great bokeh, and is sturdy as hell. Only downside is that it's much heavier than a 70-300 mm G or VR lens, and you'd need at least a monopod.
In order of what I'd get from the info you gave me:
- 70-300 mm G lens.
- a Sigma 70-300 mm cheap lenses and read reviews and user reviews that compare performance.
- used 80-200 mm f/2.8
- new 80-200 mm f/2.8
- 70-300 mm VR