I used to own Pentax Dslr for 2 years. I was using kx then k5 until 2012. I switched to Canon 7d in 2012 summer.
At that time I did not know much about DSLR brand. All I take into consideration was the camera body. When I decided to buy my first DSLR in 2010, I chose Pentax kx. because it has the best value on the market. The specification of the body is very good. Canon did not have one on par at the same price. When I decided to upgrade my kx in 2011, I chose the Pentax k-5. Once again, the specification of k5 is amazing. All the reviews online proved that it is one of the best bang for the buck at that moment.
After using k5 for over one year, I made a big decision. I sold all my Pentax gears, and switched to Canon 7d. Let me explain my reasons.
If you compare the hardware of Pentax k5 to Canon 7d. I would say some specifications of k5 are better than 7d. The most important aspect of DSLR, the overall image quality of Pentax k5 is a lot better than Canon 7d. It has 2 stops more dynamic range and one third to half stop better noise performance. That is really a noticeable difference. Plus Pentax k5 was like $300 less expensive than Canon 7d in 2011. So why switch to Canon 7d?
First, lens selection. Canon has a much broad range of lens selection. You just have so many lens can choose from. Canon makes lens for every useful focal length. Moreover they make multiple versions for same focal length. For example, they have 3 versions for 50mm. Usually 2 versions for most of the lens they make. This is really a major factor for DSLR shooter. Lens sometimes is more important than a camera body. For Pentax, it is really limited. less focal length available. and no choice over which version to buy. For example, if I want a 70-200mm lens. for canon, there are total 4 versions we can purchase right now. but for Pentax only the 60-250 f4 available. Pentax user is really stuck with only one choice. I do not like this at all.
Second, third party product compatibility All third party lens manufacturer like sigma, tarmon make lens for canon. but they do not make some lens for Pentax. So once again Pentax user has less choice. Moreover, all those accessories on the market always compatible to canon, but not to Pentax. Pentax is hard to acquire all kind of accessory. Some accessories have really good feature, but Pentax user can not use them..It is not good for photographer again.
Third, is not related to gear itself. more about service. Canon is a much bigger company than Pentax. It has more customer service location. Even with local repair store, they all definitely repair canon gears. but only a few have the ability to repair Pentax gears. It is not very convenient for photographer. One more thing. It is so easy to rent Canon gear locally, but that is not the case with Pentax. Usually only very few online rental store has Pentax gears. Moreover, if you are doing event, and you find your battery dead, the chance is that you can still borrow one from other photographer since most photographer use Canon. Whereas if you use Pentax, you are left alone in this situation. Too bad..
As you can see from my 3 major reasons, it is really a good move from Pentax to Canon.
I have been use Canon 7d for one year now. I do not regret the move.
Hope this is helpful for people who want to take photography seriously whether as a hobby or profession. Camera body evolve at fast speed. but the overall image of the company changes slowly. All those aspects I mentioned can not be changed within 2, 3 years. Therefore I would say if you want to dedicated to only one brand. Choose big brand.