my top picks would be You Can't Hurry Love and I Can't Help Myself. those define the 60s "classic motown sound" to me

After that, the motown sound evolved to a point where it was still excellent but not unique, in terms of a recording label. obviously in the late 60s, 70s and even 80s there was some very fine music coming out. and the artists began to establish more of their own brand and sound. but IMO the label didn't have a totally unique and original approach to music any longer.