Personally I think defense is MOST important in zone.
Yes, you can 'target' a player with low defense pretty easily in M2M but you can also target the player with zone, in a way.
But zone has the worst defensive rebounding and worst turnover generation of all 3 defenses. The main benefit (besides stamina preservation) is low FG%. 2-3 is best 2pt defense and 3-2 is best 3pt defense. For bigs, block is really important along with defense but block is much less important at the 1,2 and 3. Speed is also really important for guard defense but you still need Def rating.
In my opinion, Defense rating is the least important in Press. Press relies on Speed for turnover creation and Ath for fouling. Obviously defense is a component here but if I'm skimping on Defense in any set, it's probably press.