The verdict
If you have no email tool yet, pick Brevo first. A list and a few automated emails will do more for a small B2B team than a webinar nobody hears about.
If you already send email and a rep gives the same demo or onboarding session every week, I'd pick eWebinar and let it run without a presenter.
You can use both. eWebinar runs the session, and its attendance data can reach your email tool through its API, webhooks or Zapier. Test with one session and check what arrives before you commit. I would not buy eWebinar for one-off live events built around guests or news.