I personally was more of a right paddleman myself. I do think left paddle has more character development because you do play through his story more in story mode, but I think right paddle has more of an immersive feel to him, he has more heart/charm. I think people whom recreate pong on flash sites and all those other kinds of pong reiterations never remember the storyline.
The left paddleman is a young, jive-kicking youth fresh out of school, and he never aspired to become anything. He comes over to his friends one day and he is introduced to this new-age sport called pong. That day was very momentous to left paddleman. He yearned to live a life as a professional paddleman. So he ventures about the city having a few matches here and there, and a sports-agent sees him perfectly execute the reacharound. The rest of the game goes through some lengthy story, interestingly enough there was no love interest, although you can consider the game of pong to be a true love of left.
But the shocker is when he arrives to the championship. Left slides in, impressed and proud of his winning streak. He's determined. A grand feeling of surprise fills Left's face as his opponent slides in from the top. Right paddleman is the friend whom has started it all in his life, and he himself is the champion. I think the motion-capture that they used to capture pure shock is amazing, I think Allan Alcorn should recieve more praise for this role.
But all in all I like the Right Paddleman more because he is a very great supportive character and surprises you from his wit and charm to his determination and pride.