I'd say the power ceiling of semblance or aura has is lot lower than planeswalker magic.
But it is (i think) also possible to be a very weak planeswalker.
Aura and/or semblance might be easier to learn or use at first, but planeswalker magic levels cities and nations at the higher end of the power curve.
It depends on how you define power.
As far as sheer innate personal OOMPH goes there are not especially magical animals who can squish walkers all day and night. Even before the great nerf walkers primarily were hard to kill, harder to catch, and just had a ton of options. Post great nerfing they're even less innately powerful, and easier to kill.
The biggest difference between ordinary people and walkers as far as power goes is that walkers are innately talented at manipulating and aware of Mana flow. However this can be quickly leveraged by allowing them to learn spells quickly and gather Mana bonds with lots of places.
MtG magic, or at least the main form, is geomantic in nature. It relies heavily on external power sources and generally speaking favors skilled or clever users over powerful beings.
It is possible for MtG mages to achieve great workings beyond the scope of a hunter, but doing so requires gathering resources, allies, and doing lots of prepwork. It's less about their personal might and more about their ability to manage logistics and sapient resources. Essentially they stop being comparable to individuals and need to be evaluated at the organization level.
Aura users are supernaturally empowered combat monsters. Most MtG mages would have trouble dealing with them unless they were one of the few skilled, paranoid, or fast enough to keep up with them from a standing start.
That said most MtG mages more than a few years into their magical education know not to try to play punch wizard with a knight or a barbarian, much less an aura user.
Their role is behind the front line summoning meat shields or doing area control, or even farther back doing crafting work.
Now an MtG caster with aura... That's a bloody nightmare.
