Late to the party, but I think the question paints it as being a bit black or white.
What I like, is good cover that's evenly spaced, and CQB typically does this a lot better than woodland, by nature of there being mostly man made things everywhere, often including the physical site itself - buildings.
I hate the uncertainty provided by thick vegetation, it often comes down to who has the more ammo or the higher rof. I might see someone through a bush, but if I engage, I only have 30 round mags. Even if I shoot first there's no guarantee BBs will make it through, and high cap users can just saw holes through things to hit me. It just feels a bit cheap.
Woodland also invariably involves a lot of "Hmm... That guy's just out of range" moments, where opposing forces are just slinging 80 tons of plastic through the air at each other, just out of range, but there's no cover between you or them in order for anyone to close the distance. People know if they move up first they're the one who's going to lose, because the enemy already have their guns up and then can see where you're going. They just need to laser beam all their shots just ahead of where you want to be and you're done.
CQB is a lot more about out thinking people, because there's ample places to go and things to do in order to cover your tracks, the cover is generally BB proof so there's no uncertainty, and high caps offer no advantages because there's good cover for reloads, tactics and angles of exposure can be utilised a lot better for getting team mates to protect you on reloads, and it's often single shot only so people have to learn to lead their targets.
That said, there are good woodland sites, but I find that they're often paintball sites first, airsoft sites second. Paintball is played in fast paced game modes in small areas with lots of cover, so you rarely get instances where people are out of range, the cover's always good and well spaced/planned out, but airsoft guns have better accuracy, so you can play the angles a lot more effectively.
