I chose the +150k option because the question itself refers to being an EFFECTIVE curator, and personally that means my votes have enough value to have a noticeable effect on the author.
Obviously, with more than 15-25k you can be a curator who makes a difference nowadays.
That seems to be the most common answer so far! Will be interesting what others say. I agree with you on the 15-25k number for sure. People do tend to appreciate upvotes from people in that range. 🙂
I appreciate all votes, no matter where they come from, because I know the true value of each one and how hard it is to reach a certain amount here on Hive.