Onkyo/Integra = shitty HDMI boards that fail after a year then even after being 'fixed' fail again a month later. Older DTRs of the 5/6.6 level had an issue with going from Optical or S/PDIF to analog or back where you would get no audio, they claimed this wasn't true at all.

D&M = shitty NICs and UARTS. Anything on a network besides their AVRs and they blame the network for why their AVRs streaming services stop working. The UARTS go to 'sleep' and stop accepting commands unless you constantly poll, they blame Control manufacturers saying its Crestron, etc who's UARTS sleep.

Yamaha = THE FRACKING WORST 232 protocol EVER, also they seem to change between needing RTS/CTS and NOT needing it. Changing from 3 wire to 4 or 5 wire 232 and their volume control is based on taking the current volume and adding 1 to it, problem being if the AVR doesn't respond correctly with the current volume level it goes to SHIT!

NAD = Base units use different HDMI chips than the mid-range and higher units/ They are also built at two different places! so HDMI cables, extenders, Fiber solutions will work with one AVR but NOT another.

Pioneer Pro = Just didn't like their feature set & control.

And that is my review of every AVR manufacturer we have used at my company