Have you been more successful daytrading stocks from the long side or the short side?
That's like asking if you think the next person you will see will either be male or female,
Or, more or less, if the coin will be heads or tails this time,
You should be completely neutral, have no bias for direction, on a day time frame scale.
If you are an investor in a mutual fund or something...then it's Ok to say you think it will go Up,
It's kind of silly, from a day perspective, to have more inclination for one direction over another,