Question: Runes into ThunderLord's?

I just wanted to briefly get the boards opinion on what runes are currently stronger(or not) based on the state of the game. My idea was, with thunderlord's decree being so popular( most champions seem to run it on a per game basis), would a bigger commitment to magic resist runes yield better efficiency in this Meta? For Example: a support bottom selects MR quints over armor quints. Is it still better to get the armor in that auto-attack lane or is the prevalence of TLords warranting that extra MR(assuming both lane opponents use TLords)? I'm sorry if this post was placed in the wrong area, just wanted some feedback. Thanks.