The prefix <mis> is almost always pronounced mɪs. Here are some example words:
misalliance misadventure misappropriate mischief misdeed misfortune mislead misnomer misogyny mispronounce mistake misuse
misanthrope misanthropic(ally) misanthropist misanthropy
rather oddly are pronounced with mɪs by some people and mɪz by others.
There are a few words which begin with <mis> where this is not a prefix. For some of these the pronunciation is mɪz. Examples:
miserable misere misericord misery
The word miser and its derivatives have the pronunciation maɪz for the first syllable.