Google translates both of them to be interesting. And which can be used for a funny guy?
- A child on a roller coaster exclaims 楽しい!
- A physicist sees an unexpected factor in the equations describing the speed at the top of the third hump and muses 面白い.
Those are the extremes. There are quite a few things which can definitely be described by both, including people with slightly different nuances.
楽しい人 does not mean "interesting/fun person" for a rather curious reason. Since it relates to internal emotional state, 楽しい defaults to talking about the speaker's emotions. 楽しい人 translates to "person I find fun/enjoyable-to-be-with". It can have a romantic connotation, or a meaning close to "person I enjoy chatting with".
面白い人 similarly means "Person I find interesting", not "Person who is interested". It also has the implication of "person who is humorous", but only if the speaker enjoys that humor. This is probably what you are looking for, but realize that neither is really making an objective statement.