I don't know why people say Bootstrap is "bloated" and Foundation is not. They are pretty similar, in fact the Foundation CSS has a larger footprint (86kb vs 65kb). I think people say it because Foundation feels more "raw" but this is not a selling point in my opinion. In fact I find that Foundation's biggest flaw is that it's components don't look that hot.
I will also agree Bootstrap is a quick and easy way to get something up. I would argue it is quicker and easier than Foundation, but many people with serious CSS skills don't want to work with it for some of the reasons I brought up. I think that Foundation is more flexible and extensible which is a big strength.
However, none of this is that important for a landing page, I have been able to build landing pages quite comfortably with both and don't think either has a huge advantage here. A landing page isn't a huge task either so I'd try doing a rough design on paper and building with both to see which you like best.
I will probably concede though for most "product/fit" finding experiments Bootstrap may still have the speed advantage, particularly if you are not that familiar with CSS (in fact I credit Bootstrap with teaching me a lot about CSS).