The best? Hard to know or remember.
But, those that invariably stand out are fully dual mono....right back to individual transformers.
In a fairly new home for us and I want to keep my audio clutter to a minimum, so my tube mono amps are packed away still...but I'm getting entirely adequate hi-fi from a Pioneer Elite A9 fully dual mono receiver today. I think it was $600.
Now, its not being asked to push a hard load for speakers, the room is only about 15 x 18' - but it sounds extraordinary. It's a rare 2 channel only receiver with no digital inputs or out, a 'direct path' switch, display off function for best sound. Radio, remote and a surprisingly clean MM phonostage complete its tidy function list.