Should I get a mountain bike or a regular comfort/cruiser bike?

I'm looking for a bike that I will ride to school every morning and back (I live about 3/4 of a mile away) and that will last a long time. I hope for it to cover a lot of ground with each pedal, so I considered a mountain bike, which I think is durable and made for speed. But, on the other hand, is a regular... show more I'm looking for a bike that I will ride to school every morning and back (I live about 3/4 of a mile away) and that will last a long time. I hope for it to cover a lot of ground with each pedal, so I considered a mountain bike, which I think is durable and made for speed. But, on the other hand, is a regular cruiser somehow better? My friend has one, and it's pretty comfy when you sit down and all, but the when you change the speeds it doesn't really feel different and you have to pedal a lot to cover the same ground my old (now flat) 5-speed bike did. I'm consider either Walmart or K-Mart (cheap! :D) and around $100.

Your thoughts?
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