The Fedor/Arona fight was scheduled for two rounds. Arona clearly won the first round and the second round was even. After two rounds you could definitely argue that Arona won. The fact that the judges saw it even after two and had it go to a third round is what gave Fedor the win.
In my oppinion the three that looked the best against Fedor are: 1. Crocop (a long tough fight where Fedor was a little ahead all the time, but where Crocop showed why he is a legend). 2. Nog (he expected to win and did well imo.) 3. Rampage (he did well and looked to even Fedor in speed of movement until Fedor woke up to th threat. I would think Nog is currently the biggest threat to Fedor. Another legitimate threat is Barnett.
If Cro looked the best against Fedor, then no ones looked that good. I don't think Cro looked great. He stunned Fedor and that was it. Arona gave Fedor a good fight.
If by 'Nog looked the best against Fedor' you mean, Nog got his head caved in in both the 1st and 3rd fights (2nd wasn't going well either) while getting dominated losing literally every minute of every round, then yes, Nog looked best. :think