They are all nice names, but I like some more than others. I wouldn't choose "London," as that was the silver-medal winner in the Olympic show jumping this year. "Absolute" to me sounds like vodka. My favorites are "Winter Hill," "Touch of Winter," and "Grayscale" (would not suggest the other spelling unless you're British or Canadian).
I heard a neigh. Oh, such a brisk and melodious neigh as that was! My very heart leaped with delight at the sound. --Nathaniel Hawthorne
Just so you know, there is a very successful grey equitation horse out there named Vancouver, as well as a grey A/O hunter named Absolut that wins a lot too. Both names are very nice, but if you're planning for this horse to do the AA circuit you will not be the only one with the name. London, Winter Hill, and Greystone are my favorites