Recs.
Updated
Funtoo Linux is a Gentoo-based OS that uses a git-based Portage tree. Run by Daniel Robbins, creator of Gentoo.
SpecsUpdate
Pros
Pro One of the only sane distributions out there
Changing a desktop environments should not break your system. Running on older or non-mainstream hardware shouldn't make it impossible to install your distribution. Basically, if it's a computer, your distribution should be able to run on it. Funtoo is a rare distribution where you can actually do that. Also, you can use rpm packages and they will mostly work. I replaced 4 distributions with Funtoo, because software and drivers that worked only on one of the four distributions worked on Funtoo out-of-the-box. Skype also works. Funtoo might have a steep learning curve at the beginning, but afterwards you will be in the driving seat, and you will not hit a wall afterwards: editing source files, creating your own packages, running on other platforms that are not i686 or x86_64 will not require finding another distribution. If you want to learn one distribution that works, this is it.
Pro Binary packages of hard-to-install stuff
It comes with a binary Debian kernel, which means the graphic tablet is working properly. Also, browsers like Firefox and Chrome are available in binary form, so you don't have to compile everything from source if you lack the time. Also, the arduino-bin package really simplifies development with arduino, so you don't have to setup a cross-compiler etc.
Cons
Con People who don't want to learn shouldn't use it
The whole funtoo user experience is tailored so you can use the distribution on every single piece of hardware that is probably in your house. With Funtoo, it's only a question of time to get something running on a piece of hardware. Unlike other distros, the learning curve might be steep at the beginning, but once you're over it you are completely in the driving seat. But that means you have to learn continually.