If you plan on a grip down the road, save up for the KP, if you need an IR remote go for the K-70, If you are going to use large lenses, they both will do fine since when you get into long lenses you probably have a lens foot to mount on a tripod or monopod.
I personally went from a K-50 to a KP and love it, mostly due to the lack of AA filter and better resolution, but over the past year I have gotten much better glass than what I started with. Since the sensor and most capabilities are the same, if a budget needs to be kept, the K-70 and the 18-135 is the way to start, and if in a year or so you want to try the KP, or perhaps the newest flagship, (if it is released next year,)you can sell the K-70 body after getting your initial use out of it. Glass is the important thing with a 24 Megapixel sensor.
---------- Post added 07-21-18 at 11:55 AM ----------
Originally posted by CarlJF I would suggest the K-70 and put the extra money on some lenses. A K-70 with some good lenses will be much more useful than a K-P with only the kit lens... Or, sais otherwise, lenses are much more important than the camera itself. Between the two cameras you,re looking for, the best will the one with the best lens.
What Carl has said is very true, the difference between some older, inexpensive lenses and a more modern design becomes much more evident when the sensor is as good as the one in the K-70 and KP.