Re: Best stadium atmosphere?
Argentina by the looks of things is mental. Fans look like an 80s rave is going on in the stands. Them, Serbians, Turks and the Greeks seem to have the most intimidating atmospheres by far. Not watched as much Brazilian supports, but wouldn't surprise me if they're also not far behind Argentina.
Germany definitely has the best supports from the major European leagues. Dortmund & St Pauli on average strike me as the two best German supports. Feyenoord seem to be lunatics and Ajax as well from limited viewing seem quite a rowdy lot when they want to be. Don't really rate Italian supports except for maybe Napoli, very few away supports in Italy that have impressed me. Torino are supposedly very good though. Rapid Vienna from Austria also look incredible. A Villa lad swears down they're the best support to have ever come to Villa Park in the UEFA Cup, and from a video they seemed to match Celtic pretty well at Parkhead.
England is pretty dire these days, too many regulations and restrictions, prices pricing out working class fans and generally a lack of segregation that European fans enjoy. Celtic are by far the best home support in Britain, with Rangers arguably second especially with more Ultras groups forming. United are pretty much the best away support in Britain for me on their day. Have everything you want from an away support, though its generally only on display in cup games these days where more 'lads' get tickets. Leeds & Villa make up the top 3 away supports in England. Celtic I haven't seen too much away, they seem generally to have gotten much better away from home over the years as the Green Brigade have risen in prominence.
Can't really believe someone suggested Anfield. Its only special for maybe 2 or 3 games a season these days, and they're pretty much just another average support nowadays. Just like United, Leeds, Chelsea, Newcastle etc they can be special on their day, but even a lot of their fans will tell you only the back part of the Kop really gives it a go these days.
FC United are arguably the best and most consistent support in England, but lack the overall numbers to be in discussion with the likes of Leeds, United & Villa who take 000s to away games without fail.