There are many diferent and detailed sources out there. Everything depends on your personality.
For example, why do you want to learn group theory? Because you want to know its mathematics inside out, or simply because you want to understand representation theory in QFT? The two goals are very distinct. There are many other reasons to learn group theory, for example, if you want to understand groups in chemistry, then a pure math book won't be good for you.
What is your knowledge level in set theory and proofs? Do you know the basics? Are you a bit proficient in it?
Are you interested in discrete (finite) groups and symmetries, or in continuous groups and symmetries?
Do you want a pure math book with rigorous constructions and proofs of every statement, or is a book for physicists that is at places nonrigorous and more intuitive good enough for you.