> And then what? I get used to one flavor on my desktop while a completely different
> one is more suited for me to play around with on my Raspberry Pi?
On the desktop if you want any hope of Google returning usable support answers you'll run either Fedora (or Red Hat Enterprise Linux or CentOS) or Ubuntu (or Kubuntu or Xubuntu). There are people having a great time with other distros, but they're also much more DIY affairs for the most part.
Similarly, if being compatible with what the rest of world is doing on the Pi is important at all to you, run Raspbian on it. Since Raspbian and Ubuntu are both Debian derivatives, learning one pretty much learns the other too.