I would really recommend you get one of the 16MP sensor cameras (K-30, K-50, K-5, K-5II, K-5IIs) or newer (K-S1, K-S2, K-3, K-3II). The K-50 is probably a great choice. K-S1 is another good, affordable super compact choice. Even a used K-5 series can be found for good prices. K-S2 is well-liked. The K-30 has a good following, but some develop a problem (you can check its subforum for details)
K-50 and K-S1 seem like good, affordable, reliable choices. K-S1 is not WR, but you don't need WR for older manual lenses anyway, since the lenses are not WR.
Why 16MP and newer? Because these cameras have great ISO noise performance, live view, most have WR, they have good backwards compatibility, and a good amount of MP. The sensor industry has some sort of steps, leaps, and the 16MP was a rather big step in terms of noise, dynamic range.
Originally posted by Canada_Rockies he thing I notice the most is going from CCD sensor that showed excessive noise at 800 ISO to the K-3 is the noise level is way lower with the CMOS sensor. In common with others, I prefer the low ISO colours on the CCD sensor in the K10 to the colours on the CMOS sensor. On the other hand, getting to be able to use higher ISO numbers is a huge benefit.
Yes, for higher ISO is a big issue. And I think the colours can be fixed by shooting raw and proper post processing, or just using a jpeg mode like Film reversal. But many people say the CCD sensor colours are special, so what do I know
That said, for manual lenses and old film lenses, you might want to consider the brand new, slightly pricier (though still fairly priced) K-1. It has an FF sensor. This means the sensor is as big as 35mm film, so you can use your old lenses to their full potential. APSC sensors don't use the corners of those lenses, so the apparent FoV changes. Top of the line camera, Pentax flagship, should last you for a long, long time.