The verdict
For a small B2B team that wants to sign up, run a test webinar and see where the data lands, pick Livestorm. The free plan lets you test the room and the registration flow, and the credit pricing is easy to estimate once you know your audience size.
If you run regular, larger events, need payment processing or certification features, and are happy to talk to sales, pick GoTo Webinar. It also helps if you already use other GoTo products.
I'd pick Livestorm for most readers of this site. Whichever you test, run the same session in both and look at how cleanly registrant and attendance data reach your CRM.