At least Epic says so:
“Enum classes are supported by all compilers and encouraged as a replacement for old-style namespaced enums, both for regular enums and UENUMs.”
Besides same functionality, I would opt for the recommendations of any API provider.
And from a personal point of view I don’t like to use namespaces for something thats not intended (I know the safe_enum idiom and fellows, but strong enums are here to overcome ancient limitations and workarounds).