For me... I hate getting beat by RPOs. I have a solid defense against most of them that usually gets me a pick 6 - IF I'm facing a formation that I know has one. I've pretty much memorized the most common ones... but every once in a while someone springs something new on me.
RPOs are another "feature" that's been added to the game to make new / unskilled players feel like they can compete.
So what do you hate facing?