You are perfectly right: "You can't go wrong with either of the choices, both are good".
If you do not mind about price, go for Canon 5D Mark IV with AF versatile tools and excellent video skills (with the new firmware). If you have manual lenses, if you want a better dynamic sensor (36Mp>30Mp) with a better signal-to-noise ratio, if you are not a sport shooter (with autofocus lenses), if you don't mind about video, go for Pentax K-1.
And one thing more, the price:
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Pentax K-1:
US$1900 D-BG6 Grip included (US$250 value)
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Canon 5D Mark IV: US$3300 body only and
US$3650 with BG-E20 Battery Grip (US$350 value)
So, you can buy two Pentax K-1 for one Canon EOS 5D Mark IV, the Pentax camera being half the price of the Canon one.
About lenses, the problem is not real as you actually do not need all the focal lengths and even if it were the case, you actually can find what you desire in different brands at a very good price performance ratio. Therefore, it's a matter of cost then of needs or vice versa...
Last edited by teiki arii; 05-14-2017 at 12:49 AM.