I really like Dumoulin. Obviously he doesn't have the most exciting style of racing, although he can be quite aggressive if he has the legs for being so, but then again as he is a TT specialist I don't mind it. And as many gc contenders nowadays aren't very aggressive I'd rather root for the guy who wins that way than the one who loses that way (looking at you Monsieur Romain "I made the race" Bardet)
I also really have a soft spot for Landa and Lopez. I mostly like Landa because of all the funny drama that's basically constantly surrounding him and has made him a CN forums favorite, a little bit like Betancur. Lopez, well, we still have to wait, but the way how he rode in last years Vuelta really appealed to me and almost reminded me on a young Contador. Then again I thought exactly the same about Aru in 2014 and although I still like him he didn't quite live up to the expectations.
And then of course there is the man in my profile pic, Enric Mas. I jumped on his hype train quite early so I'll probably support him for his whole career, but to be fair, the likelihood that he actually becomes a gt winner isn't big likely. I can still hope though.
Anyway, right now I'm still rooting for Nibali and don't really need anyone else I can be a massive fanboy of. I'll see in a few years who I'll be rooting for but it's not like that's an active decision I'm making now. Time will tell.