I've had 4 or 5 Onkyo A/Vs over the years, and haven't had issues with any except the very first one (mid level 400 or 500 series back around 2000.) That one had a audio board that went bad, but was replaced with no great hassle under warrantee. At the time I upgraded to my current (an 808) I saw all the talk of heat and HDMI reliability issues with Onkyo receivers, but by then, there was another issue keeping me loyal to Onkyo:
My HT rack had evolved into a fairly complex one controlled with a bunch of macros, learned commands, etc. on a URC MX-810 remote. Each receiver upgrade had required a minimum of re-programming, because the Onkyo command codes never changed. The prospect of having to a learn new control logic for someone like Denon and then having to completely re-program and de-bug the remote was the tie-breaker that led me to roll the dice one more time with Onkyo.
And the results have been fine. I've never had any trouble from the 808. It seems to run cool and I love the sound. And, as expected, installing it was again a non-event as far as remote programming was concerned.