I liked Deepwood Sniper from 3.0.

It wasn't perfect, and could probably use a cleanup for 3.5e; but if you want to go for a sniper feel, I thought it did the job well.

Another option would be to homebrew a Prestige Class. (I say Prestige Class because standard classes are, by and large meant to cater to a larger group than a Prestige Class. EX: There are several kinds of Paladins. A Knight of the Chalice on the other hand is much more narrow. There are several kinds of Sorcerer, but a Dragon Disciple is again, relatively narrow.)

As for a base class to use...

Ranger is probably one of the better choices; though you could see about going Rogue and allowing said homebrew Prestige Class to use Sneak Attack from further and further away.

Just ideas of course <. .> I'm sure there are other ways to handle it too.