I suggest you play all of them at the same time. This normally involves borrowing your friend's systems and televisions/handhelds, lots of concentration, and an empty bladder. Then you could film your feat and post it on YouTube and getting tens of views.

What I would do is start at the beginning of the list with Final Fantasy I, and eventually playing them all. So, I pick FFI.

Or, if you are still having trouble deciding, get a bunch of girls to kick you in the nuts. Then, however many kicks it takes to make you drop/pass out/require medical attention will be your answer. Five kicks = FFVI, seven kicks = FFIX