Grey elves are actually better than Sun elves, unless you're a Str-based gish.
Grey elf: +2 Dex, +2 Int, -2 Str, -2 Con
Sun elf: +2 Int, -2 Con
So the grey elf gets a bump to your primary stat and a secondary stat, and a penalty to a secondary stat (con) and to a dump stat (str).
The sun elf gets a bump to your primary and a penalty to a secondary.