Madara win both rounds
Madara stomps handily in round 1 (much faster than Zeref, he's smarter from what's shown, more versatile and has perfect susano), and in round 2 he gets the Juubi to sick 'em. Even Zeref and Acnologia would be powerless against an ocean-drinking, country-ruining monster.
Let us just hope zeref doesn't forget the value of human life and kill 20k people let us also hope madara won't be one of those people. And so far the only thing we hear about the ten tails are stories and folklore not actual fact. If the ten tails was all they made it out to be how would it lose to a human ? A chakra using(which comes from the ten tails) non ocean drinking non country splitting human. Atleast in shows/comics/manga when they beat their Gods they have some legit reason but somehow the sage just did it. Couldn't the ten tails just split the continent the sage was standing on in half and continue drinking the atlantic? If the ten tails was all the folklore made him out to be he would not have been able to lose. That is just like saying I can fight God and win by sealing him in the moon. <--- Clearly BS because he can just erase my existence.
Also even if we were going by ten tails feats um acnologia destroyed a island by just toying with them in one hit. If me playing around eradicates and trace of an island it is quite certain that me being serious can eradicate a country.
First round I will give to madara because Zeref isn't that much of a badass and madara's hair is pretty spikey.
Second round I give to zeref and acnologia because acnologia can just fly in(while zeref hops on his back) and just eradicate the island with madara and juubi and fly off.