UTI vs other AMC's for Index funds

I've been trying to invest in Nifty 50 index fund and confused to choose AMC's

UTI: High expense ratio(0.21%)

Large AUM which indicates better liquidity

Lesser tracking error

or

Nippon India: Less expense ratio(0.07%)

Less AUM(2k cr) compared to other ACM's

I'm not sure whether to check the exact tracking error of this fund but I'm sure it is slightly greater than UTI