No one vendor has the best-in-class solution for all release management needs. Who has the best repository technology, or the best parallel development capabilities, the best support for Agile or DevOps? These will always be a matter of taste, subject to conjecture, and a source of disagreement. In practice, tooling decisions are often made in large part by the negotiating skills of the parties involved.
The point is that an organization needs to select the best release-management tool for the job at hand and needs the vendors to agree to make sure their tools work together. But beware -- vendor-created, point-to-point integrations are fragile. Development teams need to make sure their release-management tool vendor is exposing APIs through Web services and that those integration points support the team's process and do not impose the vendor's process.