The idea for this poll is genius....the kind of genius idea that makes one resentful for not having thought of it first!. I was stuck between SQ1 and 3. I think that 1 has the easiest puzzles of the series. Even if it has some bad dead ends, it's so short that it isn't difficult to just start over completely.
I think that SQ3 was rather obscure for the fact that it took a lot of aimless bumbling around before you accidentally stumble upon what the plot is supposed to be. Also, that Astro Chicken game is really hard! Still, it's my second fav in the series for its atmosphere, music and hum