Do you truly need 750W? Most modern, single GPU setups rarely need >450-500W if a quality PSU is opted for.
The SeaSonic Focus+ series is great quality, and appears to be in stock (in the US at least) moreso than the G2-G3 etc.
https://pcpartpicker.com/products/compare/bkp323,WrNypg,64cMnQ,jWFXsY/
for the G series the 750W is when the 10 year warranty kicks in, 749 and below will only have a 7 or 5 year warranty.
I too suggest the G3 as the one to focus on. got one for nephew couldn't be happier.