You should get Far cry 3 it is one of the best game I played so far even though I have assasin creed 3 but have not finished it yet taking my time slowly with that. and hitman I am gettin it soon have not played yet so cannot comment on it. but Far cry is fun game with an awsome story and lots do to in there and it'll make your price worth it same as ac3 but far cry 3 is a lot fun. I still have not finish far cry 3 since I am doing all the side stuff first and doing one mission at a time for the story.
In terms of being an actual Assassin, AC1 all day. Sure it was repetitive, but the actual assassinations were the best in the series, and it was before the series starting going absolutely crazy (Minerva, Juno, need I say more?).
And Altair is by far my favorite assassin. If I had to rank them...
AC1, AC3, AC2, AC:Revelations, AC:Brotherhood.
AC1 and AC3 are pretty close. I'm just glad we're done with Ezio.