I would like to acknowledge Gregory’s Great Flatwound String Odyssey- from 2017-2018 (indicating that it wasn’t the first and certainly won’t be the last...).
I have been down that path several times with rounds. Just dipped my toe into flats and find the Chromes (first choice) to be rather awesome. But I digress... the best way to find what works for you is to journey on your own string Odyssey- it is always subjective, time consuming and dings the pocket book a bit. But to know what is best you have to try the rest. It is more than what the sound is from the string, the tension, the feel, the friction of fingertip on steel....