diy COLA DRINK (2nd attempt. score 5.1/10)

my 2nd go at : diy COLA DRINK (from a bottle of flavoring).
Result : meh. 6/10. wouldn't buy again.
mine :
Cola flavoring essence from ebay (££4 ?).
sugar.
would prefer to use sweetener but I'm a fan of Dr Norm Robillard diet and he doesn't seem to approve of sweeteners apart from Erythritol (if I recall correct).
As the others are all 'probiotics' to some degree.
anyone who ..
1. knows decent cola flavoring brand
2. has a good recipe from SCRATCH
can post it if they want (or even make their own youtube video).