I have both and prefer March Madness. My reasons are:
1) Control - I prefer the feel of the game and being able to "cut inside" like I can in March Madness. Most of the time in ESPN, I'm "locked out" of the paint, no matter the defender, and it really ticks me off.
2) Real World Events - Ever seen a college player get benched by his coach for inappropriate conduct in a VIDEO GAME? Now you can! Players can mess up in a variety of ways. Grades, partying, etc... and you decide what the suspension will be, so the NCAA stays off your back. You can even have boosters "pay" players to come to your school. Personally, I've steered clear of such manuvers, but I'd love to hear what happens if your caught after such an activity occurs.
3) Recruiting - The full year recruiting is pretty cool, and I got some "decent" prospects before signing day. Was was a TOUCH disappointing is that I ended up with a TON more kids coming at the last minute... which I suppose is realistic, but I'd have liked to recruit more of them "on my own".
4) Overall experience - What can I say, I love the game and think it's amazing. My UW Huskies won the "Big Dance", and I need to start my 2nd Season as head coach of the team. Here's hoping Larenzo does the same thing in real life.
Both games are good, like I said I bought them both. But I've played MUCH more March Madness. It's in the game!