I don't really have a favorite single mod but, my favorite modpack is Orespawn. It adds so much tools, ores, mobs and different dimensions into the game. It's definitely my favourite. Speaking of that I haven't played Minecraft in a while.
Cats, Dogs (Any type of pet)
Loud people
Cold weather
When someone forces me to do something
Terrible music
Trolls
April Fools
Anti-Bronies
When I need something and it's not there
Terrible TV shows
YouTube ads
When people are doing stupid stuff on purpose
That's a few things that really annoy me. I have more but I don't want to list them all.