Who's a lot more effective in between MCU‘s the Ancient One (Tilda Swinton) as well as additionally Doctor Strange (Benedict Cumberbatch)? In 2016, Marvel Studios formally opened its doors to magic and also mystic arts in Scott Derrickson's Doctor Strange. The film introduced fans to brilliant neurosurgeon Stephen Strange, who's unable to use his hands after being in a car crash. In the hopes of fixing them to practice his profession once again, he explores other means of healing his body, leading him to Kamar Taj where he meets the Ancient One.
Initially skeptical of the magic given his scientific-based background, Strange is convinced of the endless possibilities after the Ancient One reveals to him other unknown realities, including the Mirror Dimension. Convinced of the power of the mystic arts, Strange begs the Ancient One to take him under her wing to train, which she eventually does. Their mentor/mentee relationship was cut short, however, with the death of the Ancient One at the hands of her former student, Kaecilius (Mads Mikkelsen). Strange is positioned to be the Ancient One's successor as the Sorcerer Supreme, however between the two powerful mystic arts practitioners in the MCU, that's actually a lot more effective?
Doctor Strange explains that a sorcerer gets better by “study and practice, years of it.” This means that to be able to get better at sorcery, one must expand their knowledge of the matter by studying and also perfecting their execution of spells by practicing – both should be done consistently as various experiences also help in the progress. Strange has been learning fairly quickly; he sifted through resource materials during his time in Kamar Taj, explaining why he's quickly able to pick-up certain magical abilities, with his intellect playing a part in all that. He has also found himself on the battleground fighting the likes of Dormammu, Black Order member Ebony Maw, and Thanos (Josh Brolin), where he applied what he learned by reading literature. Still, it's not enough for him to get past the Ancient One in terms of mastery of the craft as she simply had more years to hone her skills, not to mention the experiences she had along the way. By the time of her death, she was around 700 years old, and many of those years were devoted to learning more about the mystic arts. The fact that she had more time to practice magic in itself gives her immense advantage from her contemporary that started his training only a few years before.
What about Strange's countless battle with Dormammu at the end of Doctor Strange? It's not confirmed how many times he died, came back, and bargained with the villain in the hopes of saving the world, but it could be years in terms of normal time as the sorcerer locked them both in a time loop. While Strange lost every single time he approached Dormmamu until he got what he wanted, this experience gave him the opportunity to exercise the skills he learned training in Kamar Taj, allowing him to perfect them. The problem is, he barely added anything new to his repertoire. Without any access to books or any various other resources, he wasn't able to expand his power set. Meanwhile, the Ancient One fought different foes, learning new things coming off of those battles and adding new capabilities via studying for years, still giving her a clear edge.
This is the current state of match-up in between the Ancient One and Doctor Strange in terms of sorcery skills, but that doesn't mean that it won't change. The Ancient One said that Strange is supposed to be the best of them in Avengers: Endgame, meaning that, as he continues his arc in the MCU, he will get better – and ultimately become the best; he just may not be at that point yet. It's also worth noting that Strange still isn't the Sorcerer Supreme, which methods that he'll become much a great deal a lot more reliable in the coming years, particularly as he studies alternative realities in Doctor Strange in the Multiverse of Madness.