What's the best landing page platform that allows you to integrate advanced forms

What's up guys, I run a local cell phone resell business as a college student on the side and it's earning decent money however I want to take it to the next level by building a landing page where I can collect leads and give offers a lot more efficiently than messaging on Facebook.

Users can select the details about their device such as condition, storage, network, etc. and the form gives them a custom offer. it sounds a little complex but should be fairly easy to make.

I have a lot of experience in the e-commerce/landing page niche but have never really messed around with custom forms that can give a response. (don't even know if there is such a platform/application that can even do this).

Any help is appreciated, thank you guys!