Plenty of release tests out there on the new BSA Goldstar 650 and no doubt there will be back to back tests done against the Royal Enfield... so if oyu had the chance... which one would you buy???
I would go for the Enfield, and not just because I have owned a 500 single and still have my 1937 Model A, but I have found that singles over 500cc get to be a bit 'grumpy' at lower engine speeds. The twin Enfield will be better in that respect and probably smoother and not as tiring on a long ride. Both weigh around the same, similar price and quality so what ever tickles your fancy.
That BSA has a kerb weight of 469 lbs. and the Royal Enfield Interceptor is 445 lbs. If they are trying to emulate British bikes of the 1960's they need to go on a diet. My 1966 Bonneville was 363 lbs. dry according to the manual. Is Indian steel heavier?