は別として【はべつとして】

は別として means "apart from", "setting aside": you put one thing to one side and say something about the rest. It follows a noun directly.

Setting something aside does not say it is unimportant. You are only leaving it out of this judgement.

"Whether or not"

After a question with かどうか, or a pair of alternatives with か…か, は別として means "whether or not": the question stays open, and the second half holds either way. The verb or adjective is in the plain form; a な-adjective or noun goes straight before か.

"Except"

With a person, は別として often means "except": that person is the exception, and the rest of the sentence covers everyone else.

はべつに別にして means the same and sounds a little more conversational. はともかく is close too, but it often hints that the set-aside thing matters less than what follows.