I can't respond for XMPP, but the same question probably goes for Matrix (or any other open comms standard). Reasons you might use Wire over Matrix are probably

I can't respond for XMPP, but the same question probably goes for Matrix (or any other open comms standard). Reasons you might use Wire over Matrix are probably if you prefer the app's UI/UX to any of the Matrix clients out there, or if you like some of Wire's more unusual features like sketch-sharing, or if you want compulsory E2E crypto, decent group VoIP calling, or a system which does not consider itself beta. Conversely, the reasons you might use Matrix over Wire is if you want an open standard for the protocol (simple HTTP+JSON), or an ecosystem of different clients, servers, bots & bridges, or Apache licensed impls rather than AGPL, or implementations which were built from the outset as FOSS, or to decentralise history across an open federation of multiple servers rather than be forced to federate via a centralised service, and bridges through to things like IRC, Slack, Gitter etc.