Hmmh, it depends... they did recently make some rather good two-channel (stereo) receivers, the HK990 and HK3390 of which the former was quite remarkable, but their more recent surround AVRs are a bit "meh" - totally decent, but none of them made me think "yeah, I'll take that over the equivalent Yamaha". Mind you this is all from reading online and some very very brief hands-on, so I may well be wrong!
To be honest, what really puts me off Onkyo is the slew of HDMI board failures and overheating issues that they've had with their AVRs, which has kept happening for many generations. I also prefer the more natural sound of Yamaha - each manufacturer does do some degree of sound signature tuning on their devices, and the amp/processing tech that each of them choose also has some degree of impact on that. In an ideal world they should all sound the same and not "colour" the sound in any way, but we don't live in that ideal world.
Hmmm. Why does the Quote box not work?
>> In an ideal world they should all sound the same and not "colour" the sound in any way<<
I agree. If I want to colour the music, I can do that. I shouldn't need special effects in order for the sound to be reproduced. I have an old Pioneer AVR, a VSX5300. It was a nice unit, very early Surround Sound. So early in fact, it doesn't even have a powered centre output, so one either needs a powered centre or an amp. I decided to get a non-powered speaker and use a Rockford Fosgate single channel 50W amp to power it and it sounded pretty good. If I wanted better or more prominent dialogue, I could adjust the gain on the centre amp separately and all was well. The sub had to be [self] powered off one of the front channels because there was no sub output either.