The verdict
If email is how you reach people and you have nothing solid in place, I'd pick Campaign Monitor first. A list you own is the base for everything else.
If you already send decent email and a rep repeats the same demo, training or onboarding call, I'd pick eWebinar. Record it once and it runs on its own.
They work in sequence: the webinar produces registrants and attendance data, and the email tool follows up. eWebinar has an API, webhooks and an official MCP server, while Campaign Monitor has an API but no MCP server. Check what reaches your CRM from eWebinar with one test session.