I think that a public proposal could be romantic if the situation was right. Candlelight, music, fancy restuarant, etc. Private proposals I think would be more intimate for the couple. I have been engaged twice. The first one was a trip to the jewelry store to pick out a ring. Then he gave it to me on Christmas day in front of my family as a wrapped present. However, I don't consider that a real proposal since he never asked me nor put the ring on my finger. As I mentioned in a previous thread, jj and I never officially got engaged so there was no ring to make a proposal.
Therefore, I pick other because I think a proposal could be a pretentious thing. If it is public, it seems that the couple wants a lot of attention. If it is private, well as la petite moi said, obviously the woman would already know that the proposal was coming. I think that the best type of circumstance is when you know you are going to get married, the words don't have to be said because you can feel it inside of you. That, imo, is true love and means much more than a fancy proposal.
Plus, I have a bad memory so I probably wouldn't remember much about it anyway.