What's better on mages Hp scaling or armor seals?

People get the HP scaling when they bring offensive blues instead of MR.

I personally prefer armor because there's a lot of AD mid laners, and even if it's not against AD because it allows you to fight in their minion wave more safely. Later it can reduce ADC damage slightly, which can be helpful.

scaling hp for most since mid lane gets levels faster than 3-4 other people on their team.

The math alone says that hp is better at level 6. And as a late game scenario, I think all but 1 champion scales armor, which means that armor runes become less effective as the game goes on.

Edit: I forgot to mention that since there is so much armor shred/pen in game now that armor is kinda weak..