Here is something another member said that sums up what method you should choose perfectly:
Why do I rarely see big cubes mentioned in these arguments? I really think it's an important consideration. Ask anyone whose main event is big cubes and I'm sure they'll tell you that they're glad they chose CFOP. I don't like the way people blindly recommend Roux without mentioning big cubes.
Also be aware that every single method has a large number of algorithms. It's something you cannot escape no matter which method you choose, so instead of running from them, you should quickly overcome that fear if you really want to get sub 30.
Personally I'd give the following advice:
Learn CFOP if you want to be fast at everything. If you want to be fast with big cubes, definitely learn CFOP.
Learn Roux if you're especially interested in 3x3, and you like the idea of intuitive solving.
Learn ZZ if you're not interested in big cubes, and you like the idea of rotationless solves (especially good for OH).
Play around with all methods. At very least learn the steps of the big four (CFOP, Roux, ZZ, Petrus).