I've got all three football games (NCAA, Madden, and ESPN), and you can make a case for each one.
NCAA '05 - Unfreakinbelievable stadium noise! The atmosphere that EA created in this year's version is truly a work of art, and neither NFL game (Madden/ESPN) can touch it. Matter of fact, the NFL games are kinda' boring after playing a couple of seasons of NCAA. Stadium / home field advantage actually affects your players! So if you have a rookie HB during an away game at a big stadium, his composure rating will suffer (as a rookie) and he will not play as good, or might even fumble more!
The play itself is great, but you'll find yourself struggling against top-ranked teams while creaming the lesser teams (just like real-life college ball!). I like the head tracking of the receivers while the ball is in flight.
ESPN2k5 - Nicest eye candy of all three. The ESPN license is top-notch (except for the poor lyp-syncing), and Sega added all kinds of gimmicks to it's franchise mode (almost too micro-managed for my tastes). However, the stadium atmosphere is the lamest of all three. Your home crowd will be going nuts for a 1st and 10, but will be dead silent when your D is trying to stop a critical 3rd and 2. WTH?!
And make no mistake, Sega's ESPN2k5 is much more arcade than sim. For instance, you can "power-up" your RB (by holding down the power button), as well as string moves together (spin-juke-stiff arm-spin-jump-etc). It is not a bad game (like I said, you can make the case for any of them), but it definitely has more of the arcade style that many gamers prefer.
Madden '05 - What can I say - it's Madden! Some people are stale on the franchise, so they push ESPN over it simply for something new. But EA always upgrades, and this year is no different. They really went after defense this year, and if you are familiar with the Madden series (especially last years), the first thing you'll notice is the game is FREAKIN' HARD!! (really tough on All-Madden level). Defensive AI is superb, and with the new Hit-Stick and individual defensive audibles, a whole new level of realism is being realized.