I want people to daven for me if I have a serious illness but I also know that some people feel that
אין הברכה מצויה אלא בדבר הסמוי מן העין
which they interpret to mean that it’s better not tell as if it’s hidden from the world you are more likely be cured ( receive a bracha)
Which is right ? Or can one choose one’s own derech?
First of all, H-shem should sent you refuah shleima b’karov, b’toch shar cholei Yisroel. Please send me your name so I can daven for you.
The answer to your question is not clear, both ideas in a way are correct, and it would be best for you to try and get the opinion of one of the gedolei Yisroel to guide you for your specific situation. If however you choose the route of אין הברכה מצויה those people who do know should be told that it is being kept quiet, so those who know should daven extra hard.
H-shem should send you a refuah shleima bkarov.