When I out started in photography, I was in High School. The beginning class (101A) was filled up, so I lied to the teacher and told him that I had taken photographer before, and I got in to 101B. After the first semester I received a D, but I was hooked, I loved it. I had borrowed my Dad's Olympus OM-1n for that class, and it seemed like a great camera, so when I returned the following semester, I had my own OM system.
Within a year, I had the opportunity to buy a Nikon F3, which I did without hesitation and dumped my OM. To this day, I think the F3 is the finest manual focus SLR ever made; despite its shortcomings, I would take one over a Canon F1, Pentax LX, or any Leica R.
When Autofocus matured and I saw the Canon EOS-1n in action (1994), it was a paradigm shift in camera technology. Once again I dumped my existing system (2 F3's and half a dozen lenses), and jumped on board with a new brand. As good as the F3 was for MF, the EOS was twice as good at AF.
Naturally when it came time to switch from film to digital, I stayed with Canon. I got a 20D, then a 1D MkII, and my latest Canon was a 1DsMkII. If you asked me then, I would have said I couldn't see switching from Canon unless there is another paradigm shift in technology.
But last September rather than drag my 1DS MkII on the trip to Paris with me, I picked up a Panasonic GF-1 with the 14-45mm and 20mm f1.7. It was great for the trip, shot nice videos, was great for eBay and was a great knockabout camera. Last month I sold my Canon, it was truly the end of an era, I had been shooting Canon for 17 years.
Just last week I purchased a used Panasonic L10 DSLR with a 14-50mm f2.8-3.5 Leica Vario-Elmarit. I barely shot 20 frames before sending it out to have it converted to Full Spectrum Infrared (if you're into IR, there's going to be a bunch of blogs devoted to that soon).
So due to a random twist of fate, sans the fanfare of technological breakthroughs I was expecting, this week I somehow became a Panasonic shooter. I'm still not sure how this happened, how happy I'm going to be with the Pano, and whether I'll go back to Canon at some point, but for the immediate future it's Canon = 0, Panasonic = 2.
Oh yeah, and for the important stuff, its still Hasselblad = 1.