Can someone recommend me a linux flavor to install an oracle database on? I have no preferences for any flavor.
Is there flavor which is easier than others? Or has less issues?
Well I believe the only platforms that are officially supported are RHEL, SLES, and OUL. So if you need support from Oracle, you'll need to stick with those distros. If that's not a concern, just pick whatever distro you're most comfortable with.
If I were to recommend one of the supported distros, I'd recommend going with either RHEL or OUL. They're basically identical to each other. For a non-supported distro, I prefer either Debian or CentOS
Linux Distros for the XE version are here
For 11gR2, they can be found here
If you just want to "Install and Go" on a 64-bit version, then have a look at HJR's GOAL as it will do the grunt work of getting necessary packages etc.
In addition to the distros mentioned by @ErikA, you can also use CentOS, which is RHEL-based, minus the RH proprietary extensions. I don't think it's an "officially blessed by Oracle" distro, but I've installed Oracle on it without issue.