Looking at the specs for the two, they seem pretty much identical, so there's not a bad decision to be made there.
The Yamaha quotes a very low standby power of 500mW, the Sony doesn't quote standby power, so that may have a bearing. The Sony has a 4 ohm switch, which may be useful if your loudspeakers are of low impedance, but they don't rate the output at other than 8 ohms, so whether the 4 ohm switch reduces the power supply volts or what is not clear.
If I were in your position, I'd buy on cosmetic appearance (a clean, undamaged unit is likely to have been well treated) and price. If you're buying used from a dealer, then warranty from the dealer may be important. These receivers are very complicated and repairs can be expensive.
S.