Crye "multicam" has had some great reviews and is rumored to be a possible replacement for the US MARPAT/CADPAT; http://www.multicampattern.com/. From what I've read, its one of the best camo patterns for multiple environments.

I also like some of the Natural Gear camo patterns - http://www.naturalgear.com/

The digital MARPAT style camo has been scientifically proven to be great camo against human vision at long ranges, but I don't think its so great at very close range.

The Realtree (http://www.realtree.com/) and Advantage (http://www.advantagecamo.com/) camo companies produce a great range of very effective products which can be utilized in very specific environments/terrain.

I like to wear camo in nature because I feel like I blend in a little better - its a psychological thing. Wearing paramilitary style gear is a red flag to many people though, and it may be better to wear plain clothes in an SHTF situation, and camoflauge them with mud/dirt/grasses/branches if you ever felt you needed to camo up. Both people and animals have keen eyes for movement, so the best camo is good cover.

Camo won't help you avoid being tracked if you don't know how to move stealthily and without leaving sign, nor provide much respite from infrared instruments. Knowledge of scent control is the most important aspect of wilderness concealment when hunting.