LeadPages has a robust A/B testing feature that lets you select two pages you’d like to run. Unfortunately, ConvertKit does not have a split-testing feature for its lead pages.
ConvertKit is more than just an email service. It also has reporting capabilities for its landing pages but does not collect as much data as LeadPages.
I will go with LeadPages as the winner here because they have more template options and tell you which ones have historically had better conversion rates.
If you want more conversions, I think LeadPages is the way to go in this category. But if your goal is to keep things simple, then Convertkit may be more your speed.
When ConvertKit announced that they would let you build landing pages within their platform, I thought, finally! Now I can cancel my LeadPages subscription.