Shouldnt you pick a Civ and make it work? But well, if you play on Marathon with that much enemys and no CS, either Huns or Mongolians are not the best to pick for you. Both of them have strength in other ways. Without any CS, Austria or Greece isn't a choice. But i think with both, you can have a nice game. With 45 CS, you can use their UA a lot. Greece can achieve a situation, they never drop any influence and that could be a cool thing. With that much competitors, i think you need a Civ that isnt just strong as Warmongerer, but has another way to get you ahead. Either Science, Trading, Culture or Faith. I personally would try a defensive strategy with Korea or Babylon. Try to get a tech advantage and then push out. I did it a few times with Babylon in Vanilla and it worked quite well. But with GnK Composite Bowman and GP changes, i don't know if they are that good anymore. Maybe Korea is a better Civ for that, because you can get better UU. But i haven't played them yet. But the increased strength of the Turtle Ship should do well, if you try a naval focus in that Era. If you choose trading, i would recommend Netherlands. I really like that type of gameplay and they have an absurdly strong UA and UI. And Sea Beggars are great as well. Arabia would be another strong pick. With the moved Trading Posts, Bazaars got stronger, their Camel Archer got an huge buff and are now very good and their Desert Start Location thing works great with the new wonder Petra and that Desert Folk Belief. But you asked for a List of five nations. Place 5 would be Babylon. Fourth would be Netherlands, third is China (i really like them a lot ), on second Place Arabia and my first pick would be Songhai. Some may disagree but i hate playing without their unique features. Biggest problem with GnKs compared to Vanilla is, that Mud Pyramids give fewer culture now, but they have +2 faith instead. Its nice, if you can catch the Holy Warrior Follower Belief. Not that strong, but a nice touch that makes your life a little bit easier. Their UU Mandekalu Cavalery is by far not as strong as Keshiks or the new Camel Archer, but with the increased strength of citys, they doing fine. Songhai now have a bit different promotions as well, check them out! The best thing about Songhai is River Warlord, which gives you 3x money from pillaging. On big maps on marathon with a lot of barbarians, nothing is better. If boosts your economy so much, that you can build a lot wonder and focus your production on Units, while buying new buildings. That may not be a working of Deity, but that's another story. If you are active, you can pop every 2-3 turns a Encampment. Another nice thing may be, that Africa isn't that full of Civs. Hadn't played it yet but picking a Europe Civ should feet strange, so much competition. Africa is like what, Egypt, Carthage, Ethiopia and Songhai compared to 13 Civs based in Europe? Well, i don't know if my wall of text helps you in any way but maybe you got a little inspiration for your next game.