Different distros for different purposes. Although, Ubuntu would probably be my main. Then I would use kali for anything "hacking" related.
I've been using a Knoppix HD install since
I ditched Microsoft and their crap. It is
intended to be a live DVD, but comes
bundled with lots of software and Compiz.
I tried Debian (on which Knoppix is based),
but it didn't "feel right" and wasn't worth
the hassle to get everything working.
The only thing I had to do was install the
Nvidia drivers and everything else just
works, except Compiz which has to be
started manually for some reason. Yes it
has its drawbacks, and I have run into
dependency hell on many occasions and more
than once just given up trying to install
something. There are things I couldn't get
working on Windows either, and then I was
really screwed because it's closed source
and there are no incremental upgrades.
Win7 is actually on a dual-boot, but I
don't even use it anymore.
Now Microsoft has even gone and screwed up
Outlook (Hotmail) and I feel like closing
that as well. They don't care and don't
listen to web feedback.