First off, I really don't think places like Bobbi Brown count. They're not competition, they're teammates. Half their formulas are identical. The only real difference is range and target demographics.
I suppose I'll go with typical answers here like NARS, Urban Decay, Smashbox.. But its tough. If we're speaking overall sales, obviously there's only a handful with the MARKETING to compete with MAC. But if you get into their biggest competition QUALITY wise... hahaha.
Someone mentioned how MAC wasn't on the top ten costmetics list? That's probably because it wasn't going by sales.
Seriously MAC fanatics. Walk around your mall and have a colour swatch day like I did. By the end of the day, I had tried on my arm, Two Faced, MAC, Inglot, NARS, Lancome, MUFE, Christian Dior, Smashbox, and a few others.
By the time I left the mall, the only ones on my arm were MUFE, Inglot, one from Two Faced, and a bit of Red Earth. MAC swatches had faded before I had even left that store.
There are very few companies that have EVERYTHING-- right now the only one that comes to mind is MUFE with Inglot as a close second-- and any makeup artist, or even makeup fanatic, with half a brain would NEVER base an entire kit on one company
MAC has its highlight hits, just like every other company, but is FAR from the be all and end all of cosmetics.