Linux From Scratch is one of my favorite distros. Having complete control over every single aspect is such a beautiful thing. However, LFS lacks the Portage system. Sure you can use any sort of package manager you want (I use the slackware .tgz method) to compile and build your own but you still have to set every single compile time flag and deal with dependency issues. Although I will never stop using LFS (or Slackware) Gentoo is fast becoming one of my favorites. The Portage system is fast (I have dsl), sets all the compile time flags(sometimes you have to tweak a little to get it JUST right) and most importantly it deals with dependencies automatically. One of the things I do like better about LFS though is the user community. Gentoo's is great but LFS seems to have a larger and more knowledgable user community. Help for Gentoo is readily available and you will always find the help you need , yu just need to look a little deeper.
Slackware: 3 servers (office), 5 desktops(office), 2 desktops (home), 9 laptops (office), 1 laptop (home),
LFS: 4 servers (home), 1 desktop (my personal desktop machine at home)
Gentoo: 2 gamers(home), 1 gamer (office-unreal cd boot for after hours :) )