Tyrande Whisperwind vs Sylvanas Windrunner? With no Priestess or Banshee powers, I think would be kind of even. Maybe even favoring sylvanas since her position and knowledge is entirely dedicated to warfare.
Priestess of Elune Tyrande vs Banshee Queen Sylvanas? Well lorewise if Elune wants it Tyrande can go pretty much completely invulnerable and whatever other OP shit. Banshees can do a lot of things but they still just regular units, Priestess Tyrande is a proper hero unit.
Avatar of Elune's Vengeance Tyrande vs Lich Queen Sylvanas? Night Warrior is a stupid ass name. That aside, if Elune's powers are normally OP then they should be completely broken when vengeful. But Sylvanas has her New Scourge, she can send waves and waves of horde thralls to die and be ressed by valkyrs. With Tyrande's OP AoE though it's only a matter of who's faster, Sylvanas raising them or Tyrande killing them. I think it's on Tyrande's favour.
WoW Tyrande vs WoW Sylvanas? Nobody wins. We all lose. It'll be just shitty writing and some random shit happens to stop the fight and then they turn to us random assholes behind them and call us heroes and send us off to fight instead. WoW is where lore comes to die.