The worst turbulence - and violent weather...
Well, take the "3rd planet from the sun" and point to any spots...
I have flown there. Europe, the Americas, Asia, Africa, Oceania...
xxx
Yet I consider the USA Midwest has having the worst turbulences and violent clouds.
You can encounter "cumulo-granitos" aka CB that will dismantle your aeroplane.
If you are stupid enough to try to tangle with them.
For me, as a rule, I leave them on the side, by 50 NM if need be.
I do not particularly enjoy to have my coffee wetting my pants.
Oklahoma, or Kansas, and a few other states around there can be extremely nasty.
Nastier than Pakistan, Bengal, Uganda, Phillipines or the North Pacific.
xxx
Happy contrails