I voted for Lee Sedol by 3-2, though I hope he wins 5-0.
This opinion is worth little, since I am 4k at Go and it is 25 years since
I worked with a simple neural net. And as many have observed, we can only
guess at how much the program and its computer resources will improve by March.
There are two reasons I favour the human this time. Perhaps the human
must be good enough to find one or more valid tesuji or joseki innovations
that were not in the program's training set. Lee Sedol may be capable of that,
Fan Hui less so. Even world-level human players make mistakes (in the judgement
of their peers, or find them when reflecting on their games), which is why
the human may need to play more than one unprecedented masterstroke per game
to beat a program which never blunders.
The other reason is that analysis published by the British Go Association
http://www.britgo.org/files/2016/deepmind/BGJ174-AlphaGo.pdf criticises
several of AlphGo's moves, so it is not in fact perfect either. Comments by Younggil An
also identify mistakes by the program in Game 5, while also noting that it played
the endgame perfectly.
On the other hand, Lee Hajin has pointed out that AlphaGo may only have played
as strongly as was necessary to win, and it might automatically play better
against a stronger human.
So, 3-2.
I do hope that the match terms are clear and are clearly followed, so we do
not get the kind of bad taste that was left after Kasparov complained about
his loss to Deep Blue. For example, the terms should allow the human to rest
or sleep, and the computers to be restarted if they crash or the power fails, but
they should not allow the program to be adjusted on the fly by a secret cabal
of experts. (Whether such adjustments actually happened against Kasparov or
would even be possible this time is beside the point.)