I have been exploring String Quartets over various musical time periods and still have not settled on a time period I prefer.
I have also noticed that the differences are often more subtle than in other types of classical music. It also seems that typical time markers (rhythm, dissonance, tonality, melody, etc) do not follow the usual time periods. Early String Quartets can sometimes sound "modern" and later Quartets can sometime sound early.
I would be interested you see what time periods others enjoy and your thoughts on how String Quartets have changed over time (on their own and in relation to other types of classical music).