The best way is to let the muscle rest for about a day, so the first one is about right, the other one works as well but it might be a slower growth process
if you are going to go to the gym that many times then these work out routines are both wrong for you
if you are going to do 6 days then it is much better to work each muscle group on different days
muscle does not grow in the gym, we break it in the gym, then with the right nutrients and protein we build new muscle tissue over the forth coming days when we are resting that muscle
it can take between 7-10 days for a muscle to fully heal after a heavy work out - which means it is counter productive to work this muscle again 2 days later like your workout suggests
i recommend you spilt your workouts and just do your hour or hour and a half or whatever time you do just working that one muscle group
for example if i do my shoulders i incorporate various exercises that isolate each muscle in turn, so 'shoulders' suddenly becomes anterior, lateral and posterior deltoids.
your back becomes trapezius, latissimus dorsi, rhomboids.
get what i mean?
all these muscle groups have many muscles you can work out then leave to rest whilst you do the other muscles on the other days
it makes no sense to train your biceps (or any other muscle) twice within 3 days when they still wont be healed from the first work out