Normally I'd mention that you will need to know what you're doing, etc., but I find that ArchLinux "just works" much more consistently than Ubuntu. You should be aware that ArchLinux is best run with consistent updates and that you'll be on the latest release of pretty much everything all the time when doing so. I've had only one real breakage because of this ever, so I wouldn't say it's a huge issue, but it's something to keep in mind.
Use the wiki almost religiously when you're looking into installing something and always go for using
pacman first and second something like
Beyond that it's really about exploration and what you want on your box.