I think anime animation quality peaked in the 1980s. There have been great ones before and after, but I've watched a lot from this period and I think the most impressive series (as far as animation quality goes) might be Zeta Gundam. The visual quality in a TV series is just unreal!
I think I would have to agree that overall the best anime comes from the 1980s. I also think there was some great stuff in the 90s and very early 2000s as well before anime started becoming a seasonal thing to watch online.