JFK Conspiracy Theories - Which Is Your Favorite/Most Plausible?

I am doing a History project on the ination of JFK, and a major part of it is on the conspiracy theories surrounding his death. There are MANY out there including: more than one shooter, the mob was involved, the government was involved, etc. So which one, even if I didn't include it in my short list, is your favorite and which one is most plausible? Could it have been just Lee Harvey Oswald? Thanks in advance! :)