Like many others here, it seems, I came for the WR and stayed for the glass!
I started dabbling in more serious photography with my grandfathers old Praktica with a Pentacon 50/2.8 in the mid 80s. After that one broke I got my own Camera, a low-cost Cosina with the typical standard zoom. I was glad to have actually found a zoom for so little money - until I got the first shots back from development. I really lost interest in photography at that point. My mother surprised me with a Minolta Dynax at Christmas some time later, and while this was an improvement over the Cosina it did not have the magic of the old Praktica+Pentacon and I only used this for holiday snapshots and the like.
For a long time I did not have the money to easily get good equipment (and to much other interests which were also expensive...), I used the Minolta for snapshots, later replaced it with a HP Photosmart when I decided to go digital, a good camera for the time and price, DSLRs were still to expensive for me and I still had not regained my early interest in photography.
In 2008 I finally decided to give my old hobby another try and began researching entry level cameras. While I still had some good basic knowledge about the technical side, I was quite clueless about the market situation and the available brands at the time - which might have been a good thing
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I first looked at the 4/3s, as mirrorless seemed to be a nice technology but was disapointed by the displays and viewfinders of the cameras I handled, so I checked the entry level offers of Canon, Nikon and Pentax. From the technical features I did not find anything that spoke against any of the brands, but I handled a friends Nikon and it felt like a cheap plastic toy to me, and while I did not find a local store carrying Pentax I nonetheless choose the K200 as it was the only model with WR for a comparable price. Not only did WR seem a good idea for carrying the camera in my bagpack while biking, it also hinted at a manufacturer who cared for the small details to me.
Had I done any research about marked position and available equipment, I might have decided differently (considering the frequent comments from Canonikon fans I found since...), but looking back I'm glad I didn't.
I took a bunch of photos with the 18-55 and 50-200 lens kit for nearly a year and found I started to really like my old hobby again, so I looked at additional lenses - after the initial price-shock wore of
I got the DA 35 Macro Limited. And there finally it was back, the magic I had experienced with grandpa's old GDR-equipment! My photos again had that something special I had always missed with the consumer-zooms, and with that purchase I really started into photography (and LBA...).
Over the next years I got quite a collection of current and vintage lenses. I'm not such a fanboy (not quite) that I would not occasionally consider other brands, and I'm still curious where the whole mirrorless thing is going, but so far nothing has tempted me away. If I were to switch to another system, I'd not like to go without the limiteds and some of my older lenses (K28/2.0, A50/1.2,...) and I'm not sure about using them with the limits imposed by an adapter, so any alternative should have something solid to offer.
Looking and Canon/Nikon I occasionally saw something I'd have liked (lenses like 85/1.2, 70-200/2.8,...) but in the end, being rational, I decided I would not really have gotten the equipment even if I were on the system, quite often because I could not afford it anyway! Or Sigma/Tamron had a comparable lens to offer.
That's the current situation, I got a K5 in 2010 and am not planning to get a new DSLR body right now, but if I was I'd get a K3. I got a Q last year, when I was looking for a compact secondary and recently a Ricoh GR (Wow!!). I might get a Sigma Merrill second hand as I'm quite curious about the sensor, but I don't see my main system changing anytime soon.
How long will I stay with Pentax? If they would stopped making cameras or exchanged their whole K-line with models that are incredibly inferior to the current lineup I'd probably stay till my K5 gave up at least, maybe getting a K3 second hand for a while. I currently can't imagine a technical innovation tempting me away, there is nothing on the horizon that would be important for me. I don't think anyone has a noise-free IS 100.000 sensor in the works
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FF is not a topic for me, neither is video. I'd like to see Pentax develop something in that direction, as these things are important to others, though.