Honestly and truly it don't much matter on deer.
Since the question said favorite, there are no wrong answers.

I started with a 270Win.
I switched over to a 338WinMag after buying it for an elk hunt.

After that it was just lots more fun to use the 338 than the 270.
Did it kill them deader, nope.

Was it signifcantly more convincing? Yep.
Was it more fun? Yep.

Just like that K-THUD when the bullet hits.
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Generally, Ifound high velocity screws up meat much, much more so than medium velocity with a large bullet.
That high velocity tag applies to a large number of "non-magnum" deer rifle favorites.