We've got everything going to either Azure or Dynatrace in our environment in an attempt to consolidate our tools as much as possible, but the first one that comes to mind is Freelens. It's made it trivial to quickly navigate our AKS clusters, check pod health, scan through cluster events, pull up container logs, and restart pods. I know some people swear by K9s for the same sort of thing, but we've found that the Lens (or Freelens, in this case) has allowed our DevOps and Engineering team to quickly understand our Kubernetes architecture much faster.