Lastly, I'd take MLS over NBA any day of the week! (That is assuming we have a venue similar to KC's)
As much as I would love to have the MLS here, if it was a choice, I have to disagree.
I'll ignore for a moment that Sporting Park is in KC's equivalent of Belleville and imagine that it would be built downtown or in some similarly urban location.
KC Sporting Park Capacity is 18,467
Scottrade Center Capacity is 19,150
proposed new NFL stadium is 64,000
Total MLS Home games is 17
Total NBA home games is 41
Total NFL home games is 8
Total vistors to downtown MLS: 313,939
Total visitors to downtown NBA: 785,150
Total visitors to downtown NFL: 512,000
There is a clear winner from an economic impact point of view. Plus even if the NBA required a new venue to relocate here, the venue could pull double duty with the Blues. An MLS venue (of Sporting Parks capacity) is pretty limited in its uses. So from a value for the dollar no one beats the NBA, except baseball.
Additional advantage of NBA is no silly expectations of massive tailgating parking lots.
Now I'll grant you that soccer is a growing sport so it makes some sense to secure a team asap, and NBA seems to be fading a bit of late (high ticket prices aren't helping) but I still don't think (from a purely economic arguement) that it makes sense to prefer MLS or the NFL for that matter, over the NBA.