It is indeed a logical question, and no offence taken. Personally I moved from Ubuntu to Sabayon because of the following, in no particular order:
1. I prefer KDE 3.5.* to GNOME 2.*.
2. Browsing of Samba shares with Nautilus in Ubuntu stopped working after an automatic update and, whatever I tried, I never got it to work again, whereas it worked out of the box with Sabayon. The Ubuntu forums are littered with threads about the problem. I don't know if the latest Ubuntu releases are better but I got fed up with it in the end.
3. All the hardware on my laptops work out of the box with Sabayon, but not with Ubuntu. Even the built-in memory card reader works. For example, I recently installed the latest version of Ubuntu on one of my laptops and wireless did not work. I installed Sabayon and, bingo, I was browsing the Web.
4. Sabayon's look and feel is gorgeous, in my opinion.
5. The fact that Sabayon does allow me to build packages using a source package manager (Portage) so that I can, if I wish, try to optimise applications or select certain options that a binary package maintainer may not have included in a pre-compiled package. And even try to create my own ebuilds, or modify other people's, in a local overlay for packages that are not available.
6. The fact that Sabayon is based on Gentoo, which has excellent documentation (see the Gentoo Handbook for an example of how good it is), extensive forums with lots of useful material from some seriously knowledgeable people (people well-known in the Linux world, such as Greg Kroah-Hartman, Roy Marples and so on) and a Bugzilla full of useful information and third-party ebuilds. I find the third-party ebuilds in the Gentoo Bugzilla very handy indeed, plus it has helped me solve several problems. To give just one example, it was easier for me to get a Canon printer working with Sabayon than with Ubuntu (you can find posts from me in both the distributions' forums about that).
7. A relatively small but dedicated bunch of users on the Sabayon Forum, some of whom are very knowledgeable.
8. When I moved to Sabayon over two years ago, Beryl (a predecessor of Compiz-Fusion) was installed by default, worked beautifully, and looked wonderful. In contrast, installing Compiz or Beryl on Ubuntu was something you had to do yourself and was complicated. I expect things have changed these days, but Sabayon was, and still is, more bleeding edge than Ubuntu. Back in early 2007, Sabayon 3.26 was just so much better than Ubuntu 6.06.
9. Gentoo/Sabayon has enabled me to learn more about how Linux works than Ubuntu did. Gentoo is sometimes referred to as a "ricer's distro" or a "geek's distro". Well, I enjoy tinkering with Linux (see a SL forum thread of mine on tuning performance and messing with the I/O and CPU scheduler, for example) as well as using it at home and for work, so I wanted a distro that would enable me to get under the hood. Some people want to install an OS and just use it (well, I do on some of my PCs, which is why I use Entropy on another laptop and PCLinuxOS on another). But my main PC has had Sabayon on it for over two years and I'm not considering changing to any other distro.
Personally, I use Entropy very little on my main laptop. I just prefer Portage (the total flexibility, including the ability to build packages that are not in the Entropy repository, and the fact that some packages are more up to date than in the Entropy repository). But on another of my laptops which I have set up for one of my children, the ease of use, the speed and robustness of Entropy has meant that Entropy is used on that laptop).
At the end of the day you have to try the distros and make your own comparison and choice.