If with a standard stock owon probe there is this problem, there is on the market a "particular probe" that can reduce this problem without use "a short ground" ?
It basic fundamental physic. If there is 15cm GND wire in Tektronix probe and 15cm GND wire in Owon pobe these both wires inductance is around equal.
If you compare example Agilent 100MHz (included in this one test image) oscilloscope noise Owon is far better. And THIS noise is
inside agilent oscilloscope
front end. You can not do there anything, it is made and designed so. Only accept it and live with it. Owon you can... just care that signal coming to scope input BNC is clean.
These Owons what have this extra noise, it is mainly common mode and radiated noise. It depends now how you connect it to signal. There you can also do many things for reduce this noise. And mofre fun you just need these same methods if you work with higher frequencies and with signals what include fast changes. You need these methods also if oscilloscope do not have this problem.
Buying better probe... oh well. Perhaps you see then more noise if you still use same probing methods.
1. solution for noisy Owon is. REPAIR!
2. solution is try find methods to reduce signal pollution with this Owon spread spectrum radio transmitter.
3. waiting that you are sure Owon have solved this whole case and what you buy is this improved version.
4. buy what ever, noisy or not if it meets your needs. (ther you can find tests with noisy unit and ok unit.
(and sidenote, if always or often need measure signals where level is around 1mV or less without any additional tools. If I do this I use some Bruel&Kjaer amplifier). Owon alone is just wrong tool. And many many others.
If you need this kind of scope, look also that low voltages are not fake. (I mean this vertical zoom bullshit))
Oscilloscope what have 100nV/div is not cheap and if its noise is really also good for this. Perhaps then is much better to buy active probe what can do it and use normal scope. )