Answer
Flux CD is the other major CNCF GitOps tool. Both reconcile Git to Kubernetes; ArgoCD emphasizes a rich UI and Application CRD model, while Flux is controller/CRD-centric and composable. Jenkins X and others also offer GitOps workflows, but ArgoCD and Flux are the leading Kubernetes-native choices.
Real-world example A team evaluates ArgoCD's UI-driven model against Flux's controller-based approach before standardizing on one.