I started playing the series from the original release, tbh. FO2 is my personal favorite, as the original is easily finished in a single session. New Vegas would be my second choice, though the engine makes aspects of the game less than Black Isle ideal. I'd love to comment on FO3, as I own a copy, but unlike New Vegas it refuses to run on my existant hardware. No clue. NV runs, Oblivion runs, FO3 just crashes. Tactics... Played it all the way through. Still can't bring myself to love FO Tactics. Never played the BOS ARPG, but no one who worked at Black Isle will admit it happened, so....