The Divi Theme, from Elegant Themes, is one of my favorite themes to work with.
Using the Divi Theme to make a landing page is pretty simple. I go over all the details in the video below. If you want to get 5 free landing pages you can check out DiviPlanet.com
The main reason I really love to use Divi theme is because you can easily import and export layouts. You can build one layout and use it over and over, on as many sites as you want, all with a click of a button. I have exported some of my most professional landing pages and you can get them here.