MSL is pretty decent these days. I'd guees it average attendance is or isnt far off the worlds top ten.
It's a great league if you want to play the game at a slower pace. Look at how unfit Rooney looked for Everton, fast forward a few months and he's being lauded as one of the hardest working players in MLS and everyone's raving about him.
People get too hung up on how leagues rank against each other though, theyre just all very different.