Depending on your particular use case and integrations (especially how many you use), there are two alternative hubs that come to mind: Astronomer [1] and mParticle [2]. Astronomer is more focused on building a router for any type of data and enterprise-level use cases. I have not used mParticle personally, but founders from Segment and mParticle gave thorough answers on how they differ on this Quora question [3].

Disclosure: I've done dev work for Astronomer.

[1]: http://www.astronomer.io

[2]: https://www.mparticle.com/

[3]: https://www.quora.com/What-are-the-key-differences-between-S...