The phrase "any of two" refers to a situation in which there are only two options or choices available. There are several synonyms that can be used to replace this phrase, depending on the context and tone of the statement. Some options include "either one," "either of two," "one of two," "first or second," "one or the other," "both choices," or "either alternative." Each of these phrases can be used to clarify a decision or choice between two options and can add variety and nuance to your writing or conversation.