What color is the best gear?

Solution 1:

The item categorizing goes in this order according to :

http://www.videogamer.com/features/game_guide/tom_clancys_the_division_guide_item_and_enemy_colour_codes_and_what_they_mean.html

White < Green < Blue < Purple < Yellow < Teal

Yellow items in Tom Clancy's The Division

Yellow items are 'high–end', and basically only dropped by bosses. They're like the highest quality bits of kit ever. Worth selling your entire family. That kind of thing.

The final color—teal—represent Gear Set items that were added in one of the patches and contain special abilities that stack with items from the same set. High End and Gear Set items are kind of on par with each other giving a trade-off of abilities.