Hi!
If you are really lazy, take Ubuntustudio with LTS (8.04). And do not change 8.04 to 8.10 (or other) untill next LTS release. Or switch to 8.10 when 9.04 will be near-ready. With normal release (not LTS) you'll get pissed off twice a year "just because" you'll loose your software untill someone will make packages for you (developers wait with packaging untill last moment or longer, everything can change with every beta release and it may cause errors, as it was with pd-extended and Intrepid AFAIR). And you'll have to wait some time to get your packages done. Every version now is a major rewrite, so using LTS is the only way to have your packages quite fresh and in working condition without much effort.
You can also consider other, audio- media- or pd-oriented distros (or distros supported with packages of what-you-need and/or rt kernel), Musix, dyne:bolic and pure:dyne come to my mind. Or tweaked Debian (pure:dyne?). With d:b please wait for upcoming release, 2.5.2 is very crude now.
I'm in general very pissed off with Ubuntu. It is fat and it breaks my toys. I have to compile tones of stuff every half a year. It is not always possible to compile it all... I'm under Slack now. But I don't need rt kernel. It is possible to install rt in any major distro.
You always have to choose if it is: specialised (Musix) or general-purpose (*buntu*, Fedora, OpenSUSE, Debian), fat, but out-of-the-box (OpenSUSE, *buntu*) or light, but DIY-ish (Slackware), modern (*buntu*) or with clear and obvious UNIX-like, well documented architecture (Debian, Slack) installed ONCE, forever (almost any mature release), stable (Slack, Debian - stable branch), slightly unstable, but with newer software (Ubuntu, Debian testing) or in beta stage - with newest tools but almost always something cracks (Ubuntu beta releases, Debian sid) ready to use out-of-the-box (in your case - specialized distros only), after a short while (ubuntustudio or any bigget thing with rt kernel in packages) or after heavy tweaking (installing/compiling/gathering/tweaking software, kernel, desktop env., hardware recognition and many others - like in Gentoo or Slackware). have such fancy thing like mounting your pendrive or camera in easy way, integrated mixer, network reckognition tools (avahi), so KDE, Gnome or Xfce-based or lightweight (fluxbox, IceWM). enlightenment - 17 - sorry, but I think it is unusable (I've tried it last month), it needs much more work to simply do the job with it. 16 is good.
After you'll answer to yourself - the choice will be much easyier. In my case I needed something: easy on resources stable, not so modern, but reliable software, to have live performances and many hours of efficient work without ventricular hypertension. (I'm still quite happy with Gimp 2.4) to set up once a year or two or three, with mid-size repository, with my must-have software working in 100% (It is a nomadic graphic station, so Gimp, Inkscape, Cinelerra, Scribus, Fontmatrix, Veejay, PD-vanilla, Processing and Synfig Studio is a must, with java and python software) to have pendrive, camera and tablet working in reasonable time to have my wireless card supported with high connectivity (I'm a wireless safety tester too) and some network tools (ftp client and Skype) easy to repair or tweak in ANY possible way when needed, so well documented, clear and clean in terms of architecture. easy to compile stuff on it
So Slack with KDE was the one. Debian is pretty good but it is developed much too fast for me. With Slack my tools are supported within few years. Or I can compile things on my own. Settings, additional packages, tweaks are left untouched after reinstallation, which is also a big plus. I have plenty of time (I'm working on of 1/4 full time), so having my tablet working in three days and camera in two was OK for me. This should be ready out-of-the-box, but whatever... I also like the mind-bending style of Slackware configuration, it teaches a lot.
Cheers, Luke