It's not a matter of choosing which is better in absolute terms, it's a matter of knowing what your goals are and which aspects you need to work on to get there. Anatomy with lines makes it easier to study gesture and to design clear shapes. Anatomy with light and shadows helps you to feel the volumes more and makes you better at rendering. When in doubt about what you need, like James said, a bit of both is good!

I would do some studies of both options.