Voted for atmospheric, as that would be my ideal.
However... (who didn't see this coming)
I play it totally the opposite way. Yes, my gamma is turned up high enough that only the darkest of corners can hide skulks. I tried for so long to play with normal gamma settings, but I got tired of being that skulk, thinking I'm hiding in the dark, and getting shot by a marine with lightgamma 1 set.
Yes, I know how to bunnyhop, I had to learn it since I got tired of never being able to make it down those long hallways to get so much as a bite in on a camping enemy.
YES, I jump around like my TSA issue boots are on fire whenever a skulk charges at me. I can't help it, it makes me live longer.
And the fact is that it is a competitive game. Marines vs. Aliens, a battle for domination. As much as I would really like to play an atmospheric, scary, exciting game, as long as the opposing team is comprised of people who are going to win at all costs, I've got to do similarly, or the game won't be any fun for me. Dying all the time isn't fun, regardless of how nice the map looks when you turn your gamma down and really enjoy the overbrightening effect. (go open up ns_bast and type lightgamma 5 in your console if you don't believe me, the effect is AMAZING)
So yeah, atmospheric gets my vote, but that would mean that the game would have to have hard coded limits to enforce it. There's no way to keep people from cranking their gamma. If marine jumping were toned way down, maybe the crack jumping problem would be fixed. If bhopping was coded out (easy to do, but hasn't been done) and aliens simply given a max movement speed, that would go away. Blink could be reworked into something else that's easier in the hands of a newer fade. But with Flayra's love of competitive play, this doesn't seem likely to happen any time soon.
MAYBE with NS2 we'll see something like this happen, we can only hope. But people are always going to aim to kill as many enemies as possible and survive for themselves in any way possible. That's the nature of competition, and this game isn't called 'marines and aliens make friends and have a tea party'. :p