Definitely right handed (ie, fretting the notes with the left and strumming with the right.)
Mainly because almost all written material and video lessons are done with those players in mind. If you try to learn the opposite way, you'll have to constantly keep re-writing lessons to replace "Left" with "Right".
Not to mention other hassles such as not being able to just pick up any guitar and start playing if you don't have your own guitar around.
If you decide to play the opposite way, you'll probably end up stringing the guitar the opposite way as well. Which means that your pick guard & volume controls will be above the strings unless you specifically buy a left handed guitar.
If you find that you just have to play that way though, don't let it stop you.
There's a lot of amazing left handed players around to use as inspiration :)