Redis add-ons for Heroku should prioritize true high-availability, ensuring seamless failover and automated recovery processes. Infinite seamless scalability is also crucial, allowing datasets to grow without limitations on Redis commands. High performance, multiple databases with dedicated processes, and unlimited database connections are essential considerations. The reputation and technical capabilities of the provider behind the add-on are also vital, as Redis is a sensitive piece in application architecture. A reliable and competitive pricing model is necessary for growth and scalability.