Talos reputation is excellent and it lives inside Cisco products. If your stack is not Cisco, or you need an API rather than a web form, that is where the comparison starts.
One incident produces hundreds of indicators, and per-indicator lookups are where triage stalls. Here is how to build a batch enrichment pipeline that respects quotas, deduplicates properly, and fails gracefully.
A reverse IP lookup turns one indicator into a cluster — or into a thousand innocent neighbours. Here is how to tell the difference, and how to pivot on hosting infrastructure without generating false positives.