OptinMonster

OptinMonster is built for WordPress and does one job really well, creating popups and opt-in forms that drive signups. It connects to the major email marketing platforms, so your forms automatically send new contacts where they belong. You can A/B test different popups to see what converts best, then double down on the winners.

This works best if lead generation is a priority and you want to test different approaches quickly. The plugin handles the technical bits so you can focus on refining your offer and messaging.