I bought Madden last year and then my XBOX scratched up the disc. I decided to buy ESPN around November. I liked the graphics alot better and it had very good gameplay also.
That said, there's just something about Madden that you have to love. All the new features they install, playmaker control last year, new defense control this year, mini-camp games, etc. It's awesome, even if the graphics aren't as good.
I'll definately be getting Madden 2005 but I might pick up ESPN also since it's only $20.