For a case? I've had a fantastic time with my Hyte Revolt 3 It's ITX, fits 240 AIOs and water cooling easily and even custom loops if you're careful about part choice.
It comes with a sturdy carrying handle, is easy to build in, and has been rugged enough to through into a (hard shell) carry-on bag and take with me on work trips.
For CPU choice, why Intel over AMD? The AMD chips usually have lower TDPs. In your case, because you're looking for max single core instead of max multi core, you can look at second tier chips like Ryzen 7800 or Intel 14700 which usually pair 95% of the core speed with 70% of the heat and 70% of the cores. Undervolting is also an option, and AMD makes that easier.
As far as CPU wattage and heat, there's always some kind of tradeoff. It'll be audible but with the right cooler and CPU you can keep it manageable