Voice Leading is King

Good voice leading beats any other rule. This was already valid in Bach’s times where there were fifth parallels and doubled thirds in the chord because the voice leading of the individual voices was so strong that it could easily justify for breaking these other rules. A good voice leading dominates anything else. Of course the ideal would be to have good voice leading AND still follow the other rules but when in doubt, there should always be a decision in favor of the voice leading.

As fifth parallels etc. aren’t as problematic anymore nowadays anyway, you can feel even more free and “optimize” your music for good voice leading. The most problematic issue you might encounter is to create bad chord voicings (which can sound very strange in complex harmonic situations) or incomplete chords. If you for example lack the third of the chord due to a voice leading decision, it might be an issue you might try to fix somehow. Good voice leading can be fantastic sounding but a chord without third surrounded by chords with thirds can sound very empty and strange. In such cases, you need to decide by ear what you feel is more important.

The good thing is that with a bit of effort you can usually fix such situations by doing the voice leading a bit differently, rewrite another voice etc. so there hardly is any situation where you actually must favor one.