Karate Monkeys are brilliant. I have one set up 1×10 which I use for everything – I have 2 wheelsets for it- one with 35C cross tyres and another one with a Chunky Monkey / Smorgasbord combo and switch between them as required (am also considering a semi-fat setup). I have a Surly 1×1 as well, but to be honest I’d happily cope with the KM as my only bike.
They are not the lightest but would withstand a direct nuclear strike and are great fun to ride.
Mine is an older model which has lower rack mounts but not uppers (I use a Salsa rack-lock seat clamp) – pretty sure the newer one doesn’t have rack mounts at all so you may want to look at the Ogre as an alternative which is pretty much the same geo but more set up towards touring etc.
Incidentally the Karate Monkey does have slot dropouts but has a direct mech mount – I’ve never found it to be an issue, I’m assuming the Cotic has the same slidy dropout / mech hanger business that my old Roadrat did which I agree was a bit of a pain.
The others you mention also sound like good choices.