The verdict
If your team gives the same demo, training or onboarding session again and again, and the real problem is that prospects miss the live slot, I'd pick eWebinar. Record it once and it runs in every time zone without a host.
If your business is built on a list you own, such as a newsletter, a course or a community, I'd pick Kit. It is cheaper to start, and email is the base everything else sits on.
If you can only afford one and you have no stable session to record, start with Kit. If you do both, they work together. Run the session in eWebinar, send registrants to your email tool, and test what data arrives before you commit.