Hi! So yeah that's really thoughtful of you to categorize all these replies lol they look decent. As a native speaker I would say most of the time people say this as an act of surprise or as a nice way of greeting you. (Like saying ah you look great) so it really doesn't matter that much what you reply. You could go with an easy 哈哈还好啦谢谢 or any of the replies you listed above XD what you've listed are all really great replies! And you're notes on them are absolutely correct. Btw did you mean to say 离我的目标还很远instead of 太很远？

These two setences convey different meaning. The first one sounds like you're on a train full on strangers and you see this nice looking person and you think he's the only one on this train willing and able to help. The second one is more like you know a bunch of people and there's only one person out of all the others who is willing and able to help. I would assume you mean the second scenario. So yeah..