to summarize, I was a Canon fanboy for decades and justifiably so for a while when Canon's DSLRs were leading the performance curves. When I became more disappointed with newer Canon body performance compared to older Canon bodies and newer competition, I migrated towards the tools that do what I want, how i want.
I like them all! The good ones at least.
the long story
I always like cameras, got started by borrowing
my older sister's AE-1 in the 70s and having fun putting interesting shots on her film w-o her permission.
Got my own A-1 2nd-hand in '81, along w a few lenses. Shot for fun, shot weddings (hated it), shot some local fashion and event work. Didn't have as much fun as a photographer as I thought I might. Altho as a young man, being around a lot of lovely young ladies parading in strange outfits had some appeal.
Got a real job in my preferred area of technical expertise a few years later and then shot just for fun with the same Canon gear I'd always used.
First digicam I tried was a Canon A20 - the immediacy of the method had me leaving my A-1 on the shelf a lot after that! The little camera was fun and easy to use so I started pushing its limits. That took about a week. A40, A60, Panasonic FZ20, A610 and a whole lot more I can't remember. Didn't go DSLR when they came out because I couldn't justify the cost at the time.
Nikon, Pentax, and others never even entered my mind yet.
Got a used Canon G3 compact somewhere along the way and WOW! This thing really performed for IQ compared to the PnS types. Started thinking about DSLR quality... All my film was past its best before date now.
Friend got a 20D. I was envious but resigned to not buying a DSLR until they had at least 14bits/pixel and that live-view idea was also interesting.
First DSLR was Canon 40D (still have it) and it was AMAZING. IQ and all the features really got my attention. What the camera could do in raw reminded me of what I could do with film and paper in a darkroom w-o the smell and hassle.
Some I knew had Nikon before that, was not impressed with the ergonomics or user interface. Canon DSLR and PnS were all very intuitive to use.
Fun and creativity returned to photography for me.
Went thru a whole mess of Canon Rebels, just kept them mounted on lenses cuz they were so cheap used.
Nikon and Pentax, still not on my radar tho close friend had D300 and loved it. My 40D was comparable enough in IQ, I was still satisfied, maybe even smug about being a Canon user.
Nikon D70 at work, hated it, really clumsy interface.
5d2 came out, lots of hype. I bought into it.
Most massively disappointing camera I ever purchased, raw files at base ISO were obviously noisier than my old 40D and even the Rebels. I was led to believe, and had expected, much better from 5d2. Fanboys were too busy raving about its virtues to see the flaws I found in the first few hundred shots. Barely used it. After 3+ years I sold it for half what I paid, cursed every fantastic scene I shot with it because post-processing was very limited.
Avoided 50D - was obviously too noisy without even trying it. What was happening?!?
60D, liked it, bought 2 of them. Still have one, main everyday camera.
7D for wildlife with long slow lens, good camera but again, more disappointing low ISO performance. Sold it recently after a few years of light use. Got some excellent shots with it, loved-hated it.
decided I'd better put my tech expertise to some use and learn more about imaging systems
Discovered Nikon (D90) and later Pentax (K5) were starting to really perform well in low ISO range I like to use.
Tried a D5100 because it was cheap and comparable IQ to D7000 which I didn't like the ergos on.
Astoundingly great IQ! Bought pile of nikon lenses, new and used.
D800 - sounded very interesting, waited for test results.. I have to have this! I have 2, love-love them.
Bought more cheap D5100s to use as back-caps on favorite lenses.
Started selling off Canon gear I wasn't using any more.
Bought a couple Pentax bodies... strange-love them!
Considering Olympus (OMD-EM5) as it feels good in hand and performs like 60D or better
Considering Fuji (X20 to start with) because they're niche and pay attention to detail and do things differently.
All my remaining Canon bodies are now older Digic 3 class... they just perform the way I prefer and need.
I'm considering a 6D, and hoping for a low-iso-improved 7D2 to put back on my long glass.
Meanwhile, I'm enjoying Pentax more the more I use them and, along with the Nikons, I get the kind of high quality raw files for my way of working with images that Canon no longer provides. (6D and 1Dx possibly marginal exceptions)
I'll use whatever is the best tool for the shot I want to take.
I'm no longer a Canon fanboy, just a camera fanboy and I love to shoot with equipment that I know won't disappoint me when I finally get to spend some time rending the raw files to create the final look I'm after without a lot of photoshop work to compensate for shortcomings of the initial image capture, no matter how hard I want to warp that raw file.
This is a great time to be into photography. Even perfectionists can find something satisfying to use.