I slightly prefer the 4" barrel of the Model 18 over the 17 beacuse its just esaier for me to holster.
IMHO the best of both worlds is the 17-5 with 4" M17 barrel contour.
It came about as a meens of eliminating the Model 18 line,
The 4" 17-6 full underlug gets honorable mention as my second favorite K22..... but...
My "dream" gun would be a 22 lr K frame with a Model 19 profile heavy barrel and half lug.