Python 2, 47 44 34 29 bytes

-3 bytes thanks to musicman523. -10 bytes thanks to Blender. -5 bytes thanks to ovs.

Takes input as a list of strings.

lambda a:''.join(map(max,*a))

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Python 2, 47 44 34 bytes

-3 bytes thanks to musicman523. -10 bytes thanks to Blender.

Takes input as a list of strings.

lambda a:''.join(map(max,zip(*a)))

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Python 2, 47 44 bytes

-3 bytes thanks to musicman523.

Takes input as a list of strings.

lambda a:''.join(max(x,y)for x,y in zip(*a))

Try it online!

Python 2, 47 44 34 29 bytes

-3 bytes thanks to musicman523. -10 bytes thanks to Blender. -5 bytes thanks to ovs.

Takes input as a list of strings.

lambda a:''.join(map(max,*a))

Try it online!

Python 2, 47 bytes

lambda a,b:''.join(max(x,y)for x,y in zip(a,b))

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Python 2, 47 44 bytes

-3 bytes thanks to musicman523.

Takes input as a list of strings.

lambda a:''.join(max(x,y)for x,y in zip(*a))

Try it online!