Most people opting for Pujara, and while I agree he has shown a very decent technique, temperament and hunger for runs, he has also had the advantage of batting on very friendly home wickets in eight of his ten Tests to date. He has played only two Tests outside of India (both in SA) and registered scores of 19,10 and 2, so I don't think he has yet proved he is that far ahead of the players mentioned by any stretch of the imagination.
I've always been a fan of Kane Williamson, who in his 20 Tests so far has had bat in far more bowler-friendly conditions. His match saving century at Wellington against SA probably his most eye catching contribution so far. His balance when driving off the back foot hitting the ball at the top of the bounce is most impressive. What probably hasn't helped is the fact he is being too heavily relied upon in an inconsistent NZ batting order, he doesn't have the likes of a Tendulkar, Chanderpaul, Pietersen, etc, to help with and learn from.
Virat Kohli with nearly 100 ODI's (and 14 Tests);/' to his name clearly has more experience of international cricket than most 24 year olds, so you would expect his development to be at a more advanced position at this time than the others. His ODI record, and his game, looks excellent and you'd have to say that you'd strongly expect his Test stats to be of a similar standard in time.
The likeness with Brian Lara is only too apparent for Darren Bravo and quite a player to live upto, though the way he's started his Test career those comparisons won't go away soon. Did struggle in English conditions and like Williamson has done, another stint in county cricket should certainly help his game develop.
Joe Root is getting big wraps at the moment, understandably so with his start to international cricket and he does look a real player, but his career at the very early stages, but he has bags of potential and the right kind of temperament to play defining innings under pressure. While Root has received the praise so has the England development set-up with these young players coming through as more rounded cricketers than maybe they have in the past.
So I would say currently the best of this bunch in order for me is - 1.Kohli, 2.Williamson, 3.Bravo, 4.Pujara, 5.Root