This isn't close for me and I guess some people will say that I'm biased, but I will try my best to make a good argument for my choice.
First of all, I don't have to argue how the NBA is the ultimate level filled with the best basketball players, it's (BY FAR) the greatest basketball league on this planet, and when you win a championship you are a real world champion.
The NBA is by far superior in every important aspect.
The NCAA's greatest strength is it's Tournament format....I think most people would agree on that.
However, even this is not as good as the NBA Playoffs.
Some will argue that the NBA Playoffs are too long, has too many teams, and does not offer as much parity seeing as there are only a few REAL contenders.
However, one must consider that the NBA Playoffs are also very fair.
You have to win 4 times in a 7 game series for 4 different rounds.
A one game playoff round is simply not fair in basketball (as exciting as it is though).
The problem why we don't see a team come out of nowhere to win it all is because winning the NBA championship is a grueling 2 month process.
Sure a mediocre team can have a great series against a team they match up well against and "upset" them.....but it's more than likely that they will NOT be able to duplicate it later on.
BTW....for those that think there is absolutely no parity in the NBA consider the following.
From 1980 - 2002 (23 years) the NBA only had 7 different champions.
(Bulls, Lakers, Celtics, Pistons, Rockets, 76ers, Spurs)
However....since 2003 -2012 (The last 10 years), the NBA has already had 6 different champions!
(Lakers, Heat, Celtics, Pistons, Spurs, Mavericks)
And Let's think of the teams that have a legit shot to win that have never won before....Thunder, Clippers, Nuggets, maybe even the Pacers.
1997 2003 2006 2012 2013
***Lifetime Miami Sports fan (Heat, Marlins, Dolphins, Panthers, Hurricanes, and FIU Panthers)***