What time did the kinks make best music?

You're definitely in the minority for preferring their late-70s to early-80s music, but not alone either. Personally, I think their run from '65 to '71 is about as good as any 6-year run from any band ever. Both Something Else and Village Green are among my all-time favorite albums, and Arthur, Face to Face, Lola, and Muswell Hillbillies aren't far behind.

Then the Davies apparently became smitten with The Who's theatrical side and tried to make Tommy no less than 5 times with results ranging from "interesting but uneven" (Preservation 1 and 2) to "pretty abysmal" (Soap Opera) to "not bad" (Schoolboys in Disgrace). Then the "comeback" happened with Sleepwalker in '77, and while I don't rate that '77 to '84 period as highly as their '65 to '71 period, I do think it's very underrated. Sleepwalker, Misfits, Low Budget, Give the People What They Want, State of Confusion, and Word of Mouth are all, IMO, very solid albums. I don't think I'd rate any above an 8, but they're all in that 7-8 range.

To sum up: Kinks '65 to '71 is one of my favorite periods from any band ever. In fact, in that same period, I think only The Beatles were better, but not by a landslide, and I prefer The Kinks to The Stones and The Who. Kinks '72 to '75 is forgettable. Kinks '77 to '84 is solid and underrated. All together they're very much a top 10 band for me, and it's a shame they aren't appreciated at the same level as The Beatles, Stones, and The Who.