Block building is the 'art' of building 'blocks' of solved pieces in the first two layers. I.e the first steps of Petrus and Roux. Block building is very intuative and can be considered to be quite hard, both roux and petrus start of by building blocks. To get fast at these methods heavily relies on how efficiently you can build these blocks. ZZ and Petrus also rely on being able to identify 'good' and 'bad edges' something that can be difficult to get your head around. I would certainly try and look into all these methods and see how you feel as if you are good at them you certainly will get very fast with them, but if you are not, you will probably start to get very irritated quickly. CFOP these days gets branded as a bit of a n00b method, becuase of its lack of intuition, and completely brain dead Last layer. This can said to be true, but don't let people saying that that put you off. CFOP can be a intuative as you wish, you can integrate Block building into your cross, and start influencing edge orientation during your F2l. There is so much information avaliable for CFOP, and there is always something new to learn, so make sure you do not rule it out becuase of all the method hipsters say so.