I have the pink one but looked at the other colors too for quite a while. I don't find any difference in the text contrast at all. Go with whichever color you prefer.
The pink isn't really pink by the way. It's officially called rose and that's a better description than pink.
To my eyes, depending on the light and the angle you're looking at it from, it's a magenta/purple. I like it very much, certainly more than the silver or blue but it's not a girly pink if that's what you're looking for. The paper ads seem to brighten the pink up more than the unit actually is but it's still very nice.
Do you have a Sony store near you where you can see all three of them firsthand? You'll get a better idea if you're able to see it in person. I think that if anything, it would be one of those optical illusions but really, there's no difference in the text or contrast between the silver, blue or pink.