The verdict
If you run a marketing site or signup flow and a funnel stalls with no obvious reason, pick Hotjar. Run it for a week, watch about twenty recordings and you will usually find the next fix. If you ship a software product and need to know who used a feature, where new users drop out and which cohorts stay, pick Mixpanel. A small B2B team with a website and no product yet should start with Hotjar. A team with a live product and someone owning product decisions should start with Mixpanel. Many teams end up with both, because Hotjar is page-level and deep event analysis still belongs in a tool like Mixpanel.