What subject is more difficult in your opinion: General Relativity or Quantum Mechanics?

I think Relativity is more difficult. You need a heck of a lot of logic to get through it, and it's irritating when you lose your line of thought and then have to start from scratch. Whereas Quantum Mechanics is much more systematic and that wee bit nicer to try and correct. Both are difficult but it depends on which way your mind works as to which you will find easier!