I have been intimidated with the idea of 'building from source'. Recently I have been curious about trying Gentoo and BSD, but every time I do some research it is not encouraging.
Start with Calculate Linux. it's gentoo, but without the scary install, and most of the packages are binary-based. If your package isn't binary'd already, you'll have to wait for it to build. that'll take longer than you may expect. If you're testing new packages, you may have to make an ebuild. Ebuilds are surprisingly simple.
You can use systemd if you enjoy that sort of massochism, but it's definitely not (recommended) required.
As the linked writeup says, Gentoo is very much about choice. The ability to keep use flags turned off meant I had a leaner system with fewer dependencies, and I never had (pulse)audio problems all the while I had to fix family members' computers running kubuntus and such every week. No need to fix and change configurations and whatnot after every update -- set the system up once, and it'll mostly work the same way for a long long time. The other monolithinc distros seemed to break every time a big upgrade rolled. And since your programs are built against your libraries, you don't get the dependency problem of having to update all your packages just because someone bumped a popular library or two. It's all nice, and there's nothing to fear re. building from source, as the portage tooling do it all for you automatically. It just takes time, which can be a problem and one reason why I'm not running Gentoo now. Also, the last time I used Gentoo, it required a little more configuration than I think it should. As in, I think it could use more defaults that you don't need to touch unless you want to.
I can't speak for the other BSDs, but OpenBSD is totally opposite to Gentoo. You get binary packages and are mostly discouraged from building from source. There aren't that many knobs and optional dependencies. The devs want to provide good defaults and eliminate the need for twisting knobs and configuring things that can be handled by the OS. Indeed, they want to remove knobs, so that there are fewer ways to shoot yourself in the foot making the system less secure, or to just generally end up in a poorly tested configuration. You don't get to choose between five bootloaders, three init systems, seven filesystems and a few hundred kernel options. And if you go out of your way to build a very special custom system, you can expect no help from the community when you run into trouble.
A year or two later, I bought a netbook so I could unload and process photos from my camera while travelling. I had no idea what to install on it since I didn't really want to spend all the time Gentoo required, and I knew I wouldn't be updating the system regularly, which could result in a lot of pain on Gentoo if you ever needed something new. And I had too many bad experiences with all the other Linux distros I'd tried. So, just for the heck of it, I tried OpenBSD. Ten minutes later I have a working system and GIMP one pkg_add away.
As for the desktop.. well, I didn't switch from Gentoo directly. I had been running Debian for a short while. I can't remember why exactly. Could be that I had a hard drive break and I didn't have the time for Gentoo. Unfortunately Debian had been a pain from the start and one night, in a bad mood I was, for some reason I had to reboot. Which I couldn't, because apparently in some routine round of package updates Debian had messed with the bootloader. By that time I was just so sick of it, and didn't really want to look for yet another distro. I went to bed, and next morning installed OpenBSD, which had already proven painless so far.