Against the backdrop of a representation crisis afflicting Western democracies, there is a growing imperative for parties to redefine their connections with society through heightened intra-party democratic procedures. This paper employs a conjoint experiment to systematically investigate the preferences of a representative sample of 1000 English political party members (500 from Labour, 500 from the Conservative party) regarding decision-making processes within their respective parties. The study aims to address an empirical gap in the extant literature on party politics by examining members' perspectives on concrete procedural and organisation aspects related to their influence within the party. The conjoint experiment presents respondents choices between hypothetical party profiles featuring randomly assigned decision-making attributes. Each profile comprises eight attributes covering leader and candidate selection procedures, membership types, manifesto drafting, policy stances decisions, digitalisation, diversity quotas, and authority over expulsions. Randomly assigned conditions (levels) enable the isolation of the unique impact of each attribute and their combinations on members' preferences.