From Athlon Sports. Actually saw the link over on MGOBLOG this morning and they were unhappy at being #5. I'm not sure what the exact criteria are, it looks like a mix of tradition, fan turnout, game day experience, etc. Though with the latest proposed addition to the Horseshoe, that name is becoming less and less applicable, much like So Long and Thanks for All the Fish was the fourth book in the Hitchhiker's Guide to the Galaxy Trilogy.
It looks like you guys came in a close second. I have stopped going to away games because of issues with my wife's health, so I haven't been to the new Minnesota stadium or Nebraska, nor have I been to a few of the "recently" remodeled stadiums (MSU and Indiana) but pretty much think the list has it about right. I could see an argument for you guys being first, more capacity, just as loud and as intimidating, beautiful area, but I will happily take the win and say we edge out because of the age of the the Horseshoe and the more classic exterior.