Honestly, I think you will do very well with any of the above (including Onkyo).
If buying Yamaha, I would go with A20X0 or better. The A860 reviewed here revealed some significant problems and I have heard mixed reports on the A10X0, but the 20X0 or 30X0 still have solid amp sections.
Starting over a decade ago, Onkyo was plagued by overheating and HDMI failures that (due to a slow response/fix) resulted in most of us removing them from consideration. Onkyo did make good on warranty claims and it wasn't cheap! For this reason, I am sure that have addressed the reliability issues, but they still have the damage to their reputation to contend with. For this reason, they may be some of the best deals out there as they try to work their way back into consumer homes.
IMHO, Marantz is essentially an overpriced Denon. They are good units, but since D & M are one company, it made marketing sense to approach sales with the Marantz being positioned as a more expensive audiophile AVR (traditionally retaining phono inputs for those years before vinyl had a resurgence and having more analog inputs and pre-outs than the equivalent Denon). If you catch a special deal on a Marantz, it can offset the extra cost over the (roughly) equivalent Denon. Over the years, the design of Denon and Marantz has continued to take more advantage of the economies of scale associated with using the same components/assemblies. Aside from a special deal on the Marantz, the only reasons I can think of to buy a Marantz over a Denon is 1) because you need the extra analog connectivity, or 2) You just really like the look of the Marantz with the "port window".
Denon is my preference. I do think Yamaha might be a slightly better build, but all of these AVR's are currently designed to last around 8-10 years any more (on the presumption that the changes in technology will already render it obsolete in 10 years)
The reason I go with Denon is because the 3X00 or higher (as well as upper Marantz) has Audyssey XT32 which I believe to be the most advanced of the roomEQ systems along with a $20 phone app that allows you a great level of control over how XT32 is implemented including what frequency range you will apply it to. I believe that with good speakers, RoomEQ is not needed except below ~270Hz where room modes become a major influence. Of course YMMV depending on your room.
Whatever you get, I would spend $22 on a pair of these to make sure your electronics are well ventilated. these fans come with a three speed switch and I find the lowest setting is very quiet and keeps my AVR very close to room temperature.
Amazon.com: AC Infinity MULTIFAN S7, Quiet Dual 120mm USB Fan for Receiver DVR Playstation Xbox Computer Cabinet Cooling: Electronics
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