Multicam is much easier to find gear to go with (i.e. vests, pouches, etc…). The only Kryptek vests/chest rigs I have seen are few and far between and do not offer the plethora of options like you would find with Multicam. And pouches are a whole other story, I have yet to see any. A good compromise if you want Kryptek for the look or if you just want something other than the norm is to get a solid color vest/chest rig that can be worn with either pattern (i.e. tan or OD). Personally, I own both patterns and am in the process of putting together a single chest rig in tan that can be used with either, this way I can be on either Tan team or Green team at any game I go to.
Both patterns I think have proven themselves as functional in multiple environments, but I do have one concern. Like other camo patterns that are only green/tan BASED, team identification is made more difficult (Maybe ACU has a purpose after all? lol) because the color schemes look so similar at a distance. If you are willing to take on the risk of getting team-killed once in a while and if you're willing to shell out the cash, either pattern will do you just fine. If you want a more in-depth comparison, then look up spartan117gw on youtube. He's a Kryptek fan, but also runs MC and has a few videos about the two and I think he might have a video comparing Mandrake and Highlander to other patterns.