There are many threads which talk about NPC/Monster Resistances, Immunities, and Creature Tactics, but I couldn't find anything about the following:
How do I, as a DM, handle PC resistances, immunities and buffs?
Example: a Paladin Aura that boosts the group's resistances to enemy spells.
Do I outmaneuver the more resilient targets, attack the weaker ones or do I want to attack the ones with the aura so that the PCs can actually see that their strategy has provided an advantage against the enemy?
Of course I can always argument with the creature's intelligence and tactical behaviour, but in a more or less meta standard, it could reward the group for using their skills.
TL;DR: Is it better for a DM to play along with the group's magical buffs and resistances to reward the groups strategy (e.g. PCs with Auras or Blessing) or for them to try to get the best results for the enemy's goal to victory?