It sounds to me like you enjoy throwing the bike around a bit.

If that's true, get the MTB. You can ride it just fine on pavement, and if you're buying an entry level bike, they'll often come with center ridge tires that take some of the knobby buzz away. The only downside to a trail-oriented MTB is that the knobby tires will wear out quicker on pavement, and it will have a more aggressive forward position that many novice riders feel is uncomfortable, but keeps weight over the front tire for control in the soft dirt.

If you buy a pavement-oriented bike and try to ride it off-road, your skills will certainly be challenged.