What is everyone's solution to landing pages?

We are limited by our internal web development, but marketing wants to do a better job of connecting social content to website content, and our temporary solution is to build more robust landing pages.

MailChimp offers landing page builders, which work well with our email, but I personally find the design capability of MailChimp limiting (but that was a few months ago; things may have changed since then). 

I’ve done some quick searching and found recommendations for Unbounce, ConvertKit, and a few other landing page platforms, but I’d love to ask fellow experts what they’ve found works! Any and all advice appreciated, and thanks in advance!