Hello Phillip I'm not sure I understand your questions properly haha but I will do my best to answer them :D "I find him attractive" or "I find you a funny person"? I find him attractive- 난 그가 잘생긴 것 같아요 it also can be "i think he is attractive" I find you a funny person- 전 당신이 웃긴 것 같아요, 난 네가 웃겨, 전 당신이 재밌어요 난 네가 재밌어. It also can be "I think you are funny" but for the last one, Koreans tend to say 'I think you have a good sense of humour" rather than "i think you are funny/ i find you are a funny person" so if you try to say I think you have a good sense of humour would be... 당신이 유머러스한 거 같아요 -같아요, can be used when you try to say, "I think/It seems"

"I find him attractive" 1.Would I use "것 같다" for this? Because I learned that "것 같다" has a nuance of "I think something might be..." Yes, using 것 같다 is okay. Firstly, I translate it for you as"그는 매력적인것 같아." And then, to make it more natural, the final sentence is "그는 매력적인 사람인 것 같아." 2.But "I find" is a certain opinion...how to say that? Any ideas? I don't think "I find" is a certain opinion. When you get some information or realize something after a time passed or by chance "I find~" is used. If you want to firm opinion, not ambiguous, use these expressions. 그사람은 매력적인 사람이야.(this expression is proper for everyday conversation.) 그사람은 매력적인 사람이다.(this expression is usually used in written Korean)

You can say "내가 볼 땐(short for 때는)" or "내가 보기에". Like the English expression, they also express your reaction to someone or something. 내가 볼 땐 쟤 되게 웃겨. I find him funny. 내가 보기에 이건 이상해. I find this strange.