increadibly hard to judge, nether has ever faced anything like the other, spectre has only ever been beaten with magic, mahatten has never been beaten, but has never faced magic before. i think the key to this fight is what the definition of a win is, would what ozymandyis did to manhatten in antartica count as a win, because spectre is more than capable of that.
I think the fact that manhatten seemingly cant be killed, and the spectre isnt really alive, makes this almost impossible to judge