My favorites are probably the 10.8/10.9 rounded flat matte w/perspective look because it does such a nice job of looking polished without being garish (unlike the 10.5-10.7 glossy dock, which I didn't like that much) followed by the 10.2-10.4 for its sheer simplicity. 10.1/10.2 gets third place simply because they're the OGs and the pinstripe texture was fun.

10.10 onwards is pretty forgettable.

During the 10.5-10.7 era there were a number of third-party dock themes people made that worked by swapping a few image resources, which in addition to visuals could adjust reflectiveness. I had mine set to a nice studio-lit dark gray matte shelf with white 3D indicator arrows.