Gentoo is still very automated so you don't learn as much about what you are doing. That's why I like LFS it teaches you everything step by step. I saw there was another one which basically seems to do the same thing http://byolinux.org
I haven't tried it out yet though, but they seem to also walk you through the steps of installing everything from scratch.
But you asked what host is best to use for an lfs install. It doesn't really matter which one you use as long as you have the basic necessary tools to get through the first few chapters.