The verdict
For a small B2B team running webinars as a lead source, I'd pick Demio. It is quicker to set up, and its engagement tracking tells sales who to call. If you run a regular programme across webinars, hybrid and in-person events, and you need on-demand hubs, learning content or an API on your own site, pick BigMarker.
BigMarker has no public prices, and some features such as API access, single sign-on and white-label domains sit on enterprise tiers. Demio has a trial and plans where the higher tiers are priced per host. In both cases, get a quote for your real attendee and host numbers before you commit.