2. Daenerys Targaryen
Since the very beginning, Game of Thrones has been paving the way for Daenerys Targaryen to seize control of the Seven Kingdoms and become the benevolent ruler worthy of... a proto-democracy? "Break the wheel," as she puts it. To do so, she'll have to deal with Cersei Lannister and the raging Euron Greyjoy. She'll do it with the help of her army of Unsullied, a horde of Dothraki, stray Greyjoys, Jon Stark's northern forces and a pair of dragons.
The threat of the White Walkers has forced her to pivot away from taking the fight directly to Cersei. To survive, Dany will need to use the power of her remaining two dragons to burn back the Night King's army of the dead as it heads south of the Wall. Considering everything that is involved with killing White Walkers, and wights' strong association with dragons (obsidian equals dragonglass, Valyrian steel equals steel forged in the fire of dragons, fire equals... fire), if anyone is going to have the methods needed to defeat the dead, it’s probably Dany (even Cersei thinks so!).
In her visions in the House of the Undying, she saw snow falling on the Iron Throne, but that might have just been a metaphor for the Night King's attack coming to King's Landing. Either way, only Dany has the firepower and the alliances to be able to hold the city and claim the Throne, with the future of Westeros at her fingertips.