-Because (not ALL of course) the majority of his songs are upbeat/optimistic and that's the way I like to live my life
On a side note, it REALLY makes my blood boil when people say they don't like Paul because he was too 'sappy'. Or that John was clearly the better songwriter because his songs were 'deep' and 'emotional'. Pardon me for saying, but it's not healthy to be depressed! Also, happiness is an 'emotion' if I'm not mistaken, so 'Good Day Sunshine' could be considered emotional in my book!
Sorry for that mini rant there, but I was on another forum and there was a thread entitled, 'Who's your favorite Beatle' and I saw many responses doing exactly what I just said I disliked. I didn't even bother to post, I would have ranted too much