conjunction
anyhow; in any case; either way
Used to introduce a conclusion or decision that holds regardless of the circumstances; similar to 'anyway' or 'at any rate'.
いずれにしても、明日までに決めなければならない。
In any case, we have to decide by tomorrow.
いずれにしても、彼の意見は聞くべきだ。
Either way, we should listen to his opinion.
とにかく is more casual and often used to push forward despite obstacles, while いずれにしても is more neutral and focuses on a conclusion that is independent of the situation.
どっちにしても is a more colloquial equivalent, often used in spoken Japanese.
Derived from いずれ (which, whichever) + にしても (even if it is). The kanji 何れ is the standard but rare spelling for いずれ; 孰れ is an archaic variant.