Minnesota has the brand new stadium. It's nice, but quaint. Capacity is around 53K or so. They've just recently started to fill it (or come close to) consistently, but I would call the atmosphere somewhat lacking (unless they're playing a big-time opponent, or one of their natural rivals; no offense). Their fans are friendly enough as long as you don't root for Iowa or Wisconsin. Another aspect of their set-up is that there is no available public parking in the immediate vicinity of the stadium. They have some public lots a few miles away, then you take a shuttle bus to the stadium.
I've always had fun there, but that's because tons of Iowa fans go. I would imagine a small RU contingent, so that might affect things as well. Final point is that Minneapolis is a large and fairly vibrant city, so if you're into "Big City" sightseeing and entertainment options, that's a point in their favor. Not really a college town kind of feel, as the Gophers are well behind the pro sports franchises in the area in terms of public interest. Not like other Big Ten campuses where a football weekend is the main attraction in the immediate surrounding areas.
MSU is a smaller town and will have less to do outside of the football stuff. They're really good now, so I would imagine interest and intensity in the surrounding community is fairly high. Stadium is really cool with lots of character. Lots of famous games and players have competed there, if you're into college football history. The visitor's section is in the upper deck, and while the seats were fine, the ramps coming down onto the main concourse after the game had some of the worst congestion that I have ever seen. People literally standing in line for 20 minutes or so as multiple lines of people intersect at the same point. Just horrible. We went back and watched the band and waited for everyone to clear out.
Somehow through various connections we ended up with a parking pass in the donor lot right next to the stadium. Not exactly sure what the general public parking/tailgating set-up is like. I do know that their admin had set up some kind of "time limit" on tailgating at like 2-3 hours or something like that, based on some previous misbehavior. Basically, if it's a later game, you can't just park in the morning and tailgate all day long, or at least that was my impression. Their fans were cool the time I went, but the very next year several Iowa fans went and came back with horror stories about how awful the experience was, so YMMV. I don't think an RU fan would have similar troubles, though.
So to summarize, if you're looking for a more "big time" college football atmosphere, in a smaller town where college sports are king and they take things rather seriously, then MSU would be my choice. If you're looking for a broader experience and an excuse to visit a major American city and all that that entails (Mall of America! Hard Rock Cafe! Maybe an MLB or NBA game, depending on the time of year), with a smaller, more intimate stadium surrounded by people that typically place college football well down the list of things that are important to them, Minnesota is for you.