I've been using Debian (Unstable and Testing) for approximately 10 years and have been very satisfied. However, I intend to stray away from the ominous *d soon.

I've been using Debian (Unstable and Testing) for approximately 10 years and have been very satisfied. However, I intend to stray away from the ominous *d soon. FreeBSD interests me, but I've been procrastinating, and of course, that's not Linux. I have setup Debian systems over the years for a handful of people, all who've been pleased, so far - and these are first time Linux users. I do, however, spend a lot of time configuring and customizing their setups, typically with Mate as the DM. I'm not quite sure what seamless means, so pardon me if my ¢2 isn't relevant. Edit: maybe worth mentioning that I've run Arch, Slackware, PCLinuxOS, Ubuntu, Mint and one or two others. I settled on Deb. The one distro I'd (personally) advise against is Ubuntu. While it had a rather glorious beginning, it ultimately devolved.