If you join Dr RMLIMS instead of KGMU, Lucknow, you would be missing the opportunity to be a part of one of the top 5 medical colleges of India. You would miss the Georgian tag. You will miss the rich legacy attached to the institute. You would miss campus life at a huge college. You will miss the amazing infrastructure no use. RMLIMS is an excellent medical college but it is still way behind KGMC by a significant margin. It has recently launched the UG course i.e. MBBS so it will take time to establish itself.
All in all, KGMC is the better option at least as of now.
AIIMS Rishikesh, Raipur or Patna all are well reputed institutes and should not be underestimated. They are institutes of national importance and autonomous institutes of central government.
The infrastructure of AIIMS Raipur is better than most state medical colleges of India. The only disadvantage is that you won't be able to get a 50% state quota in NEET PG.
The core points of these institutes are:
Infrastructure
Faculty
Facilities
Fees
AIIMS title
Small batch size facilitates better teaching
So yes, it’s worth taking admission at AIIMS Raipur or Patna for MBBS.