Which would be a better buy? A F/VS2 diamond or a D/VS1....prices listed.?

So i found a site with real diamond images. I found a One carat Princess cut diamond with a F color VS2 clarity and very good cut, symmetry and polish. This is $3850, I also found a D VS1 with very good symmetry and good polish for $4040. Now to the eye the F looks better, how can this be? Also are the prices good? I am looking at loose diamonds......