Since it is pretty well hidden and I only found out about it in a previous HN thread: Besides a free plan and contrary to the mainstream, shodan.io has a pretty attractive one-time payment plan. It is probably not enough if you need it 9 to 5 but perfect for the occasional research.

That being said, there is also censys.io. They also don't advertise it prominently, but with their free Community Plan you can search their database for free and you'll get similar results to the free shodan search.