Pentax K10D - my main camera. This is current flagship model of Pentax DSLR line. It has 10 MP sensor and all modern bells and whistles such as sensor motion anti shake, weather proofing, RAW processing on board, etc.
Pentax ZX-L (MZ-6) - this is film camera that I use for backup and for trying my lenses on film.
Voigtlander Perkeo I - this is 6x6 medium format folder camera. Mine has no flash synchro contacts, but it has Color Skopar 85/3.5 lens, which according to what I read on the internet, is the most advanced optic for these cameras.
Primes:
Pentax SMC DA 21/3.2 Limited AL - my only non full frame lens. After much deliberation I chose it instead of FA 20/2.8 and so far I haven't been disappointed. This little lens is very much up to its limited reputation, although admittedly it is a bit slow.
Pentax SMC FA 31/1.8 Limited AL - widest of three (film series) Pentax Limited lenses. Exquisite build quality. Pictures that come out of this lens have this incredible live look.
Pentax SMC FA 43/1.9 Limited - standard Limited lens. Gives outstanding results.
Pentax SMC FA 77/1.8 Limited - short tele/portrait Limited lens. Highly recommended for portraiture, although it can be used for any other purpose.
Zooms (that are worth mentioning):
Tamron 28-75/2.8 XR DI - Actually this lens has way longer name - the whole letter soup. It replaced Pentax SMC FA 28-105/4-5.6 IF as my standard zoom lens, which replaced SMC FA 28-70/4 AL (expired due to dreadful rear element separation) that in turn replaced Sigma 28-135/3.8-5.6 IF AF Macro lens. This Tamron lens is the only one non-Pentax lens that I have. My sample is really excellent. It is sharp even wide open across the whole zoom range. I should say that as a one lens solution this is probably the best compromise between quality, convenience and price.
Short answer: why not?
Long answer: we chose Pentax by accident. After more than 4 years of being a Pentaxian I should say I don't regret our decision. There are few things I particularly like about Pentax. First, Pentax keeps backward compatibility with all of its K-mount gear ever produced. There are exceptions, but with all honesty, they are quite minor. Second, Pentax is rather conservative company (which is not necessarily a good thing) but their gear is very well thought through. Finally, given the compatibility factor, the second hand market for Pentax gear gave me some amazing bargains. All in all, even buying new gear from Pentax, I think gives one excellent value for one's money.
Ultimate answer: choose any brand you like, it most probably will give you excellent pictures anyway. First of all, what makes a shot is (heart of the) photographer. Second, comes the lens. Third, comes the camera body to which lens is attached. That would be my personal (not so) humble opinion on the matter.