Nakamura

that was easy to answer

I think someone like Caruana who has given Carlsen trouble in the past would be a harder oppoent than Karjakin.

What makes you think Nakamura?

Caruana or Nakamura or Anand

hard question 

Fabiano Caruana, the greatest chess player to ever live

i am a big fan of karjakin but i support caruana for this question

I think Giri will be next up. Giri is known for being a very drawish player, but he played sharply in the last Candidates tournament and has been winning a few more games since that tournament. 

But there are at least eight players good enough to win a Candidates tournament. It's amazing that we have a clear number 1 in the world considering how strong #2-20 are.

Who is the best person to beat Magnus Carlsen

Right now?  Himself. 

how many times should i told everyone that cornbread is the best blitz and bullet player, naka is no match to him

Lasker was a great champion. I don't think they played so much did they... So I reckon title defences might be more significant a factor in that unfathomable 'who is the greatest' equation.

So off the top of my head, Carlsen has surpassed Tal, Fischer, Spassky, Petrosian, Smyslov but not Kasparov.Alekhine has had more successful matches but against Bogo amongst his opponents - I read somewhere he picked an easy opponent.

IMHO I think Carlsen could prove himself the greatest by making a few more title defences in relative chess terms and absolute terms.

(Edit. Just done a search on Lasker who seems to have defended his title at least six times. Very impressive. So I don't think Carlsen needs to defends his title another four or five times to prove himself the greatest, but if he did, I don't think anyone could question the 'greatest' tag.)

Carlsen already has won the WCC three times in a row, in a format that gives the challenger more chances compared to most past formats.

I see people here are very biased in favor of Magnus. He has been WC for only 3 years. In the past Garry Kasparov and Anatoly Karpov ruled for more than a decade, even Anand won 3 WC matches and was WC for 6 years.

In the recent WCC, Sergey Karjakin came very close to winning and Magnus could only win on tie-break. I really think Sergey had a really good chance there . Imagine someone stronger than Sergey faced Magnus in the WC (Sergey obviously won the challenger but I don't think he's the strongest or has the best chance to beat MC), it could very well dethrone him.

No, not really. If anything, you're more biased because you're being contrarian. Holding a view just because it's "less obvious." But while less obvious views are sometimes right, more often they're not.

Even Kasparov only won, what, 5 WCC matches or something? Magnus is already on his way.

"Imagine someone stronger than Sergey faced Magnus in the WC (Sergey obviously won the challenger but I don't think he's the strongest or has the best chance to beat MC), it could very well dethrone him."

If you were unbiased then you would also be willing to imagine that Magnus plays much better than he did in his match against Sergey. But bias does tend to try to define a player by one single event, rather than the aggregate of many events.

I see that WCC is occurring more frequently than in the past. I agree he's best player atm but he has his bad days and you can't win forever. I bet in the next 3 WCCs, he loses at least 1 and MC can't even reach 10 years.

I feel quite objective in my statement tho.

He has his bad days and you can't win forever, is an argument that doesn't convince me, to be honest.

It also depends on who the challenger is. If it's Anand then you know who wins lol.

On the other hand, do you agree that Magnus was on the verge of losing his title in the WC recently?

Not fully. There was a serious chance for him to lose, but I'm not surprised he came back. I even said before the match, Magnus will be much better at coming back from behind than Karjakin, and that even if Karjakin got to the playoff, he's at a large disadvantage there as well. And just about as much could go well for Karjakin as possible, and it still didn't work. Magnus had to fail to win many positions he would normally win just for there to be a chance. When Magnus is playing at a decent level it'll be even harder to beat him.

However, I will say that there are some players that can give him some problems. Especially Caruana, who is well balanced and comes up with some very good ideas (although, a big negative is that his speed chess is quite weak for someone of his strength). Though even there I clearly favor Magnus, but it could be an interesting match and Fabiano certainly has his chances. Giri could also be a tricky player for Magnus.