Like a lot of people, I looked into Pentax when I was already pretty much decided to go with Nikon - my brother, brother in law and my friends all have Nikons. What kept me from buying a D3200 or D3100 was the lack of body controls and little compatibility with a lot of the older lenses. So when I saw a few Pentax cameras on Craigslist, I jumped at what I thought was a good deal.
Since then I've assembled a lens lineup that makes sense to me, and will make even more sense when the full frame camera comes out (I intend to buy it but only after we are done paying our mortgage, so that's a few years down the road still). I've also added a 2nd body, again because it was a deal I couldn't pass on.
Why do I stay? I think the gear I have is more than a match for my level skills, and I am having a blast using the K20D especially (the newly acquired K-r went to the wife so now she finally leaves my K20D alone and I can always have it with me). I'm getting to the point where all the controls are becoming intuitive and I don't have to think about them, I just change settings as I need to. Also, there's a couple lenses that keep me in the fold. First the Plastic Fantastic 35 2.4 - maybe I have a very good copy but mine is the sharpest lens I own other than the Auto Sears 50mm f2 - mine is sharper than all my other nifty 50s including the highly regarded M 50 1.7. The other lens that I love is the SMC-A 70-210 f4. Again, maybe I have a good copy. Mine seems to have an old type of pixie dust, the way the pictures come out just speaks to my heart. Then come my Rikenons/Auto Sears (all made by Ricoh) and my Tokina 19-35, and then a few others, I enjoy them all.
I am quite happy with my setup but of course I have an upgrade path in mind
but I'm not in a hurry.