Depending on your playstyle and map, on high difficulty (especially FTW seed maps) or play with low defense (like summoner), warding is not very helpful; but if you play a melee charactar with already high defense, warding would be very helpful. For example, if you have 30 def, the enemy deals 150 damage (common for a master hardmode enemy), you'll take 120/92 damage with/w.o. all wardings, the defense reduce damage by ~25%, but if you have 100, then you take 50/22 damage, it reduce damage by ~50%, so the more defense you have, the more reward warding gives (as long as the defense doesn't reduce all damage); and the more damage your enemy deals, the less reward warding gives.
For DPS, except summoners, lucky is normally (slightly) more rewarding than menacing (the DPS is increased by (1+dmg%)*(1+crit%), and most armor and acc. gives more dmg boost than crit boost), unless you are using low damage weapon on high defense enemies, already have crit. near 100% or using crit based equipment. But the difference is very small and both can be accepted to save money.