The answer is there is no answer.

Paddles are easier to use so to a novice the result might be better but to an experienced user there should be no difference.

As far as leather goes I am of the mind that as long as the leather is smooth and quality there will be no difference. However, having said that if you spend a lot of money on some leather and accessories I'm sure you will swear the result with that strop will be better. Of course with different leathers the experience will feel different and that feel might have psychological effects on you or it might cause you to work the strop a tad different which could cause differences.

clear as mud?