Lol, Sauron has millions under his thralldom, this is a stomp for the people of Middle-earth. That isn't even mentioning the political advantages of the forces of Middle-earth.

Edit: However how badly you want to see Westeros screwed depends on which point in time during the 3rd Age.

2nd Edit: About the only time period Westeros stands a chance is the time period after the Great Plague. 

Hobit, Chief of the Inquisition^{(Inform me of heretics)}

As much as I love Westeros, I must say Middle Earth would destroy them. 

My thoughts exactly, my original idea was to just do the westernese vs the seven kingdoms, I still think it’ll be a landslide for middle earth though.

When is our time period for Westeros? When it was like an actual united kingdom or when basically every faction has been fighting each other and they are all divided and weak?

There is a way the Westerosi could have actually defeat armies of Middle Earth a few times, but eventually they would get overwhelmed. The advantage is, Plate Armor. It is superior to mail by a large margin that could prove decisive in battles. Of course, the Lannisters, Unsullied, Starks, and all other soldiers do not wear proper armor. They just use leather because it looks cool. The goldcloaks are the only soldiers that seem to me, consistently well-armored.

Tbh those millions of orcs would probably be more of a liability than an advantage against the Others.

They would probably freeze to death.