With the Brand new Rosters X-men would easily win.
Avengers- Captain America, Iron Man, Scarlet Witch, Goliath, Wasp, Warbird, She-Hulk and Triathlon, Wonder Man and Quicksilver, Jack of Hearts, Photon, Quasar, Living Lightning, Firebird, Silverclaw.
X-men-Pheonix,Cyclops,Wolverine,Beast,Nightcrawler, Iceman,Storm,Prof X,Archangel, Havok and Juggernaut(yes Juggernaut)
Pheonix an the Professuer could make most of the avengers stand still and let Storm, Iceman and Cyclops fire at will. And for the Avengers who cannot be mind controlled Juggernaut, wolverine, havok, beast and nightcrawler could easily hold there own.