NBA is obviously a much higher caliber of basketball, and it's not even close, because most college basketball players are terrible. With that said, the college game is far more compelling and interesting. Each game is intense, unlike the NBA where teams frequently mail it in and take nights off during the endless and pointless regular season. The CBB regular season is intense from November to March, with teams scrambling to get off the bubble and jockeying for postseason seeds. And obviously the CBB postseason blows away the NBA postseason, and might be the most compelling postseason in all of sports.
The college game is also more strategical, and coaching is much more important. In the NBA, most big possessions ending in an iso with your best player, and that player is usually so good that there is little chance he can be stopped from at least getting to the basket. That's why I say the level of play is almost too good in the NBA, because the really good teams score too easily in a big spot. In the college game, big possessions are more exciting because the offense has to work harder to get a clean look.
I personally find the NBA boring, and this coming from somebody who LOVED the NBA 15 years ago and frequently went to games. They've lost me. Boring stars, boring game, boring style of play. On the flip side, during CBB season a night rarely goes by when I am not watching CBB. I can watch any CBB game. It's probably my second favorite sport behind MLB. Just a far more compelling product from every aspect aside from athletic ability.