>>4412737APSC: Pentax, Nikon's offerings are not noteworthy. I personally love my KF but a K3 Mk1/2 is a great camera. The KF makes up for the slower processor vs the K3s through a accelerator chip that's only on the K70/KF/KP/K3 Mk3. It has great DR and just EATS at high ISOs (I posted a few pics at 3200) I paid $350 for mine and they occasionally come up for that much. It's a great camera. Pentax colors are to die for and their SOOC jpegs are pretty good, sometimes it underexposes though.
On that note, look for a KP.
FF: Nikon 100%. I'm 100% convinced Nikon has the best DSLRs in FF to the point it forced everyone else to go mirrorless and add video features. People still shoot weddings with D800s from 2012. A D800 is definitely in your budget and imo its better than a more expensive K1.
For what it's worth, Nikon has better lenses. Pentax glass sucks as much as their AF unless you pay 2x as much for PLM or DA* stuff. Pentax auto settings have a little bit of a learning curve too, if you're shooting movement it needs a little help with the shutter speed.