I heard that if I reduce my voting power, I'll be able to reward more content creators every day.

That's only a concern if you find your voting power going down so much that your vote is no longer very valuable. It you're in the 90-100% range most of the time, then it seems that's not a problem and you can already vote for more people before you're notice a difference.

Which way is the most rewarding for me?

The more value you distribute, the more curation rewards you get, but it is proportional to the strength of your vote. Best bet may be to experiment a bit and see what works for you.