Well considering racial armor, I would say Charr look amazing in tier 3 racial medium armor, Sylvari look cool too as do Norn in Tier 3 (I forget which Sylvari armor I liked).
If you're asking about which race itself looks best as a ranger, then I don't quite get it considering no race looks most like they fit a certain class (though Charr and Norn do seem more like melee races) and customization can really change the appearance of some races (especially Sylvari).
For males Norn as they get epic beards, Sylvari didn't get tree beards (wasted opportunity), human beards < Norn beards. For female, a human as from what I've seen they seem to be easiest to make look serious.
Yeah I tend to visualize a ranger with a grizzled appearance with a beard (if male) or mature looking and serious (if female).