Hi Eugene, I think we need a little more context here to really answer your question. What type of hydraulic application we're talking about. Type of pumps being used, volume of fluid needed, what exactly you expect to achieve by switching fluid, etc. Are we talking about something like a large, hydraulic powered, landscaping vehicle, or some sort of hydraulic powered assembly line tool? By higher quality, what do you mean? Fluid with different properties such as viscosity and density, or simply a more refined fluid of the same type; i.e. fewer contaminants, but same overall properties?
Generally speaking, I would first look at leakage/fluid replacement rates, energy efficiency of running your system with your different fluid options, filtering, and how the fluids affect wear of mechanical components.