There are two ways to look at this question. Emotionally, since i have been using the musing platform to gain upvotes, i would definately love to delegate the steem power to musing. Just like musing upvote brings smile on my face it might bring smile on other’s faces too.
That is ofcourse the emotional part.
However, if your question is focussed to understand which of them will give you a good return on investment, then i would probably want to delegate my excess steem power to the bid bots which gives decent returns on my investments.
However, personally i would like to see a smile on muser’s face due to bigger vote given by musing