The best counterjungler is:

Your own team.

Granted I am only in silver 4, so there's that, but it seems like after 10 minutes in game most people think they're entitled to take camps whenever they feel like. With the new changes to jungle items this can put you really far behind if people keep doing it (bonus experience means camps are worth more to junglers than other roles). I don't mind giving blue or red to mid / adc if they're doing well, however with the new timers on red and blue they have become more contested as it is easier for newer players to keep track of spawns and counterjungle accordingly.

I'm not trying to create a qq thread, and I'm sorry if it comes off that way. I just really appreciate it when people ask if it's ok to take a few camps before deciding they're going to clear my whole jungle for me. Of course, I know my primary role is to be putting pressure on lanes and not afk farming. It just makes things a little harder when my primary source of gold and experience is taken away.

tl;dr: please ask before you take camps. <3