Teleportation device would be better than a Time Travel device, because with a Time Travel device, it gives people a power that isn't in reliable hands (humans). With that, we'd alter time to what we feel like it, and I'm sure most would go back and change something that made our lives worse...but, we wouldn't know what we would also change because of it. More people would be happier...but at what cost? Also, I have a weird feeling that with a time traveling machine, people would begin having more children (don't know why) and thus, we have an even more over-populated planet.
Teleportation Device just makes things simple...people like to get to places faster. This would get rid of any form of transportation, and thus, help keep the planet a bit healthier (no, I'm not a tree-hugger) but then, people would be out of jobs...but they can help make more teleportation devices ^_^

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