I might be a minority, but I’m going to make a case here for Jaina Proudmoore as the main character of a Warcraft-movie. Now first and foremost I think a Warcraft-movie needs to be at least over two hours closer to three hours long. You cannot put so much stuff into a 90 minute long thing.
Now the story would again be set during Warcraft 3. You can have a character like Antonidas, Uther or even Thrall drop some exposition about the background but generally you don’t need much: Orcs came from another world corrupted by demons, got defeated by an alliance of humans, dwarves, gnomes and elves and are now sitting in camps devoid of their bloodlust and essentially depressed. That’s it you don’t need anything else to get the story started.
The movie is split into three arcs:
Arc 1:
So, why would I now choose Jaina as the main character? Because, I personally think she is the perfect character to lay the groundwork for a larger universe and she can have a complete arc with a somewhat satisfying ending. To give a rundown:
Either the movie can start with the exodus of the Horde (meaning the very first scenes would be Thralls nightmare) which means Thrall and Medivh are introduced and give some exposition (you don’t need to know who Medivh is, it’s enough to introduce him as a powerful wizard) you can introduce someone like Grom and they sail away after some small battles and fighting.
Or you can start with Jaina traveling to Lordaeron in order to join the Kirin Tor in Dalaran meaning you introduce Lordaeron, Arthas, Terenas, the Kirin Tor and Antonidas and maybe Kael’Thas.
Arc 2
No matter how you start you can make some time skip scenes, and WC3 human campaign happens with focus on Jaina. Stratholme happens off-screen (or we have a scene with Jaina watching the burning city from afar while breaking down), and the Alliance exodus happens.
All arrive in Kalimdor at roughly the same time, maybe some small scale battle between Horde and Alliance is about to begin before Medivh sweeps in, unleashes the power of a guardian and stops the entire battle making an epic speech. We more or less skip Stonetalon and large parts of the orc campaign for the sake of shortening the movie. We are on a time limit after all.
And now the Scourge and the demons arrive. You introduce Archimonde as this all powerful demonic overlord behind everything, and all factions move to Ashenvale.
Arc 3
…where they talk right into a trap from the night elves with archers, ancients and Tyrande herself stopping them. However here we change things up: The whole Cenarius-subplot never happened and as such the night elves are not as hostile as in the original-timeline, and as such Thrall and Jaina are able to broker a deal with the night elves…especially since the undead arrive and a battle happens.
Together they wake up Malfurion, prepare the battle for Mount Hyjal and now several things happen. The showdown between Grom, Thrall and Mannoroth happens during the battle of Hyjal (Groms characterization can be changed when first introduced showing that he still struggles with his bloodlust), all while Jaina and Tyrande have an epic fight against demons, undead and all other sort of things.
And now wisps go boom, Archimonde explodes, last shot of united forces celebrating with Jaina, Thrall and Medivh slowly walks away making his famous last speech.
The End
And without many problems you can laid the groundwork. You can now make an Arthas movie, you can now make a Kael’Thas movie essentially you can go into any direction you want from this point because all the basics have been laid out.
This got longer than I wanted it to be. Oh, well.