Personally I like the AAVSO charts and lists of comparison stars because it’s easy to query via my Python code via the AAVSO API. I combine that with SIMBAD/VIZIER data to get other parameters of the target star and I can then create a good list comparison stars for ensemble photometry.
That is essentially what I do, though my code is wrotten in Perl rather than in Python.
By and large I download only the V photometry but include B and R as required. B-V, which is provided regardless, give B magnitudes but not, alas, their errors. My ensemble photometry code does The Right Thing with reported errors, which is to add in quadrature.
Out of interest, what SIMBAD/VIZIER data do you use? For my purposes all that is required is the magnitudes and the coordinates, all of which is provided in a single download from AAVSO.