When were the best tube amps made?

I think it depends what kind of tube amplifiers.

The are number of types:

1. Low power SET under 10 watt - 45, 2A3, 300B, PX25, AD1,...

2. High power SET over 10 watt - 211, 845,...

3. Small push-pull up to 20 watt - EL84, 6V6,...

4. Mid power push-pull 20-50 watt - EL34, KT66,...

5. High power push-pull over 50 watt - KT88,...

6. OTL

It also depends for what kind of speakers these amplifiers for.

@alexberger  Those look like tube names, not amps. :)

Erik, I didn't find your OP trolly.  But the SP10 is an 80s AR design and it is difficult to beat.  But when Krell entered the market around that time with the KSA50, it had that era's valve amps beat.  I still have mine and it's still very good.

Why should I care?

1987