They'd prefer to sell him to United or Chelsea or Bayern or Barcelona or Juventus..., not to (Madrid and) City, though. They must be absolutely desperate to get rid in order to think, 'well, it makes sense to sell to City, even if he wins them CLs and makes them look like the more successful project'.
They may want to sell Neymar, but I doubt they are absolutely desperate to the extent that they don't care about the implications for their ambitions in the CL and their standing in comparison to City. From their perspective, we are the least preferable destination for Neymar (if he still is as good as we believe).
Time will tell.