Yea, its different features and comes down to your own priorities. The K-70 is still so new that nobody has real experience with it yet. The K-3/K-3II is known to be quite reliable and is popular on these forums
Pentax K-3 II vs. Pentax K-70 vs. Pentax K-5 IIs - Pentax Camera Comparison - PentaxForums.com
If you cannot decide based on features (flip screen, astrotracer, burst speed, bracketing options, composition adjustment, weight, KAF4, different battery), then get the cheaper one. Might even get the classic K-3.
But to me, the K-70 looks really promising. I never need burst speed high, and don't really use astrotracer GPS. Flip screen might help me sometimes.