It is really difficult to pick one. Africa has so few tracks and even fewer in sims that I can't vote it just because I don't know many of their tracks. Kyalami is not exactly a masterpiece in my mind either. But surely they have some great ones but doubtful enough to be a world wide contender tho. Aussies have some good tracks but for me there is something missing. Bathurst is more just difficult than fun, adelaide is not street enough for me and some of the other ones (phillip island and sydney) feel a bit too modern and technical and not flowing enough.
Asia has great tracks like suzuka and motegi but some of their tracks are not fun at all for me. Like fuji, okayama and tsukuba. These guys have a thing with hairpins which I do not approve of. Every track doesn't need 2 or 3! I have to admit it that there are a lot of smaller japanese tracks and tracks in other asian tracks rarely seen in sims. And I'm not talking about f1 tracks. Google inje speedium for example. Then there is south america. Lots of nice tracks but I have to say very few of them are up to the best ones. I do like the total ultra fast speed nature of some of them. Somewhat different to other continents. And I even like the smaller and older feel of the tracks.
So after all that I am left with europe and america. Both have pros and cons. Nordschleife is definitely one 20kilometer long plus on that list! But even the usual suspects are not bad. Imola, monza, spa, hockenheim... Then you have a ton of less known but still fun tracks. The nordic countries have a great selection of smaller circuits and the middle europe is full of not well know circuits. And personally I don't even paul ricard (gt3) is that bad and I think misano is fine as well... if you also have tracks like hungaroring and zolder which could be converted to ion cannon test sites. And way too many races are held at spa. Then, depending your political views you could also include the british tracks. Lots of bigger and smaller circuits. Oulton, brands, silverstone, crystal palace, croft. Even thruxton even though I hate chicanes.
So I am going to vote north amurica. Even with the cota weighing it down (eww) I have to give it to the americans and canadians. These guys don't ruin tracks with chicanes. Mosport, road america, road atlanta, virginia, watkins, mid ohio the list goes on. And lots of smaller less know circuits. Even the rovals are not half as bad even though they do have chicanes. And north america also has those ovals which are an entirely their own thing the rest of the world only has a handful. But it is really close with europe for me.