Brother, let me educate you with the core purpose of wearing a costume. Whenever and wherever you wear a costume of any character the first thing everyone around you is going to notice is its screen accuracy. Even if a single person is going to have a hard time understanding the costume, then that night or the event is going to be a very long one for you. By saying that, what I mean is if you are deciding to go with the Groot costume then you would never be able to ace it. Because the character is CGI and no one has replicated the look which you can say is screen accurate! So going with the Rick Grimes Jacket would be a smarter choice.