I'd like to sponsor both containerd and rkt. It's important for CNCF to own and foster the foundational technology for cloud-native computing. Having both containerd and rkt in CNCF would be a great outcome for the CNCF, for Kubernetes, and for the container and cloud ecosystems. Kubernetes and other container orchestrators need reliable, community-driven container runtimes scoped to container execution. Each runtime has its own strengths and use cases, and I hope that induction into CNCF unlocks opportunities for broader collaboration. 

As for Heron, I'm not seeing the demand for Storm/Heron. For example, Google trends:

Spark still has a lot of steam, and AIUI the trend (e.g., using Apache Beam) is towards unified batch and streaming.

--Brian