They both have advantages and disadvantages. With a perfectly conditioned deck, a strike technique allows for less deck hand finger movement, but if the deck is a bit older or has been used heavily you may find a strike leads to accidentally pulling out more than one card. Therefore, for the sake of reliability, you may find the push-off technique works better for you. My advice would be to play around with both and see what works best in your hands. Practising one will help your technique with the other, so you won't be wasting your time.