IMO it's good to do both pullups and chins. Vary yoru grips with both as well. For example, do widegrip pullups sometimes, but also do some hammer grip pullups. Same goes with chins. All in all, both are great for developing your biceps and back.
FWIW it's been recommended to me that the forearms should stay as close to perpendicular to the ground as possible throughout the movement for shoulder health, so that's how I do 'em.
FWIW it's been recommended to me that the forearms should stay as close to perpendicular to the ground as possible throughout the movement for shoulder health, so that's how I do 'em.