Given its ongoing struggles at attaining demographic diversity and its key role in nations' economies, the engineering workforce receives considerable attention from researchers and policymakers. Yet, prior studies and STEM recruitment initiatives have often underemphasized the variety among available engineering jobs and careers. It therefore remains unclear which attributes of engineering work are most salient in shaping students' choices to persist in or depart from engineering pathways. This study introduces a novel conjoint survey experiment conducted with over 1000 senior year mechanical engineering students. This randomized experiment allows the authors to disentangle supply-side and demand-side factors to assess engineering job attributes' marginal influences on students' occupational preferences, as well as to examine these attributes' interaction effects with supply-side factors. Toward strengthening persistence in engineering pathways, findings suggest that broad STEM recruitment initiatives, though potentially advantageous in pre-college years, should give way to more targeted campaigns that increase university students' awareness about key dimensions of variety across engineering work roles.