Hand History

Both Villains are unknown
I think b/f is fine ott. but I wanna hear your opinion about bet sizing.
The reason of big c-bet sizing is I don't want to show him free card.

However, I think small bet is fine too. I can bet about half pot and I can happily fold if he raises.
In the book, Application of no limit holdem, it says small bet is good when villains' range is polarized.
In this case, is villains' range polarized? he can either have flush draw or straight draw.
small bet size vs big bet size. which one do you prefer at this moment?