I'm a Fenerbahce fan so I say fenerbahce ofcourse, but the other team I pick in England is probably Newcastle since the big teams have a large foreign fanbase

Both celtic and fenerbache have very 'passionate' supporters, as does galatasery. Brussia Dortmond fans are great. Id look to south amercia boca juniors, river plate, flamengo, Palmeiras. In England its hard to tell now as so many traditional fans are prices out, but maybe Leeds, City, West Ham, Millwall, liverpool, newcastle, cardiff

Celtic have pretty passionate supporters. I am a Celtic fan but I think many people would agree.