As others have said, that is seriously quick on a mountain bike. 16miles is a nice distance, I ride (or rode as I’m having a long break from it atm) 19-20miles each way and I couldn’t imagine it on a mountain bike. Commuting regularly can soon can become a chore, so being able to get it done quickly becomes important. I use a cx bike as I race cross so I have one, and I like the ability to change the tyres, fit guards, ride towpaths etc. A touring bike would be just as suitable.
I personally don’t see the point in hybrids. As inefficient position as a mountain bike without the strength and ability. Perhaps a 29″ and fit skinny wheels if you want to go that route, then you’ll have a different type of mountain bike to play with as well.
I used to do 10 miles each way, everyday and that was my only way to get to work and I used mountain bike, road bike, cross bike. All were suitable although the road bike was the least fatiguing over the long run.
Commuting regularly kills bikes so bare this in mind when working out how much to spend.