Not only do you have fluctuation and noise to deal with, you need to consider what bandwidth you want to include in your measurement. Distortion shows up as higher-frequency energy content and all of those meters become less accurate quite quickly as the frequency increases. Except the scope, but that will be the least accurate of the whole bunch and I would not count it in the mix--although it does appear to be close in this instance.
The specs for those meters are all 1% or worse (the Brymen is a little better at exactly line frequency, but your spec is wrong as well as your math) but all will likely perform somewhat better than spec. The two most accurate would be the 175 and the BM235, but all three meters agree to a lot less than their tolerances--so you already have far better results than you have any right to expect from specifications. The differences may be a result of calibration or simply due to the frequency content of the signal vs. the frequency response of the meter. As to which is the closest, there's nothing there that would allow you to even guess. 125V +/- 0.5V is probably a reasonably guess as to what you know.