The verdict
If your team is small and sales needs leads now, I'd pick Leadinfo. It is quick to set up and the value shows when someone acts on the alerts. If you spend real money on paid channels with a long sales cycle, and finance wants numbers it will accept, I'd pick Spectacle.
They overlap a little, since Spectacle also offers company identification, and both can push signals into other systems. But each is much stronger at its own job. Do not buy Spectacle with a short funnel, small ad spend or messy CRM data. Do not buy Leadinfo with low traffic or consumer buyers. Each has an API.