Class A amplifiers - which are considered the best

Yes but they were only quite low in Class A
For instance the massive KSA-250 with all it's heatsink could only do 28.5 watt Class A into 8ohms and then up to 250watts of Class B into 8 ohms. And these ran stinking hot.

http://www.stereophile.com/content/krell-ksa-250-power-amplifier-when-class-class

Cheers George

I was referring to the Krell KSA 80, KSA 200, KMA 160, KMA 400s.

Another vote for Clayton Audio S100, M-200 and M-300.

I received my pair of Pass XA100.5's a short time ago and I'll toss my vote in for the Pass XA series.

Same topology Unsound, just different models in the same rang as the KSA250 range, all with partial Class A not even 30% of their full output into 8ohms.
Like I said the only ones to have high % of Class A compared to rms output, was the fan forced Krells of 80's.
And after that the only model to get near them with good amount class A % was the Plateau Biasing (Anticipator Circuit) Krells "S" models with their Xmas tree bias lights, but they never sounded as good from many a report.

Cheers George