Given in this scenario we win the WC series, the 2nd option would be a no brainer for me, and probably the team. If you win the division and take the ALDS to game 5, that's all you get. You have the potential for 8 games with the latter option.
My definition of a successful season is making the playoffs and shooting your shot there. I suspect the D-Backs fans think they had a successful season winning 80-something games last year.