Although politicians’ personal attributes are an important component of elections and representation, few studies have rigorously investigated which attributes are most relevant in shaping voters’ preferences for politicians, or whether these preferences vary across different electoral system contexts. We investigate these questions with a conjoint survey experiment using the case of Japan’s mixed-member bicameral system. We find that the attributes preferred by voters are not entirely consistent with the observed attributes of actual politicians. Moreover, voters’ preferences do not vary when asked to consider representation under different electoral system contexts, whereas the observed attributes of politicians do vary across these contexts. These findings point to the role of factors beyond voters’ sincere preferences, such as parties’ recruitment strategies, the effect of electoral rules on the salience of the personal vote, and the availability of different types of politicians, in determining the nature of representation.