I am going to make a quad. Just wanted to know what are the pros and cons of those firmwares
Simple
SimonK = OLD REALLY OLD. Its missing so many features that BLHeli has that we take for granted.
BLHeli is used on every modern ESC get updates and fixes, comes out with new features.
Now runs on 32bit ESCs.
Oh and go for BLHeli_S ESCs
And
If you want to learn more about why blheli is so good