RC glossy is great for photos of cars and motorcycles whit shiny paint and lots of chrome. Other than that, it can be hard to look at.
The main difference between glossy and matt paper (either RC or fiber) is not so much contrast, but how black the blacks appear. First one must think about what we are actually seeing when we look at a photograph. We are not looking at the surface of the paper -- we are looking at light as it passes through the emulsion of the paper and reflects off the paper base back to our eyes. The silver blocks the light as it passes in both directions through the emulsion.
To check this out, just hold a photo up to a bright light and look at it as light passes through the back to your eyes. The blacks are no longer black, and one might see detail in the shadows one can not see normally.
The blacks are where there is enough silver to block all (or just about all) of the light from its journey thru the emulsion and back to our eyes. However, the matt surface of some photopaper scatters light on the surface of the paper -- much more than glossy paper. Some of this light scattered on the surface comes back to our eyes. So instead of the silver blocking all the light from reflecting off the base back to our eyes, some of the light is reflected off the matt surface back to our eyes -- reducing the blackness.
Now, the reduction in the depth of the black on matt papers can appear to be lower the contrast due to a weaker max black. Increasing the contrast via filters can help to some extent in counteracting this loss of appearent contrast...but not how black the blacks are.
Of course glossy RC can have problems of reflecting light strongly to our eyes. Fiber glossy is the best of both worlds -- not too shiny to have the massive reflections of RC glossy, but not the amount of scattering of light as the surface of matt paper. (matt fiber tends to scatter light even more than RC matt).
But some images look great on Fiber matt. A friend's images of native American ruins in the SW printed of Fiber matt paper have black windows that one just visually falls into -- amazing.
In the end, one just has to print several images on several types of surfaces and see for oneself what they look like and determine which fits one's vision the best.
PS -- the surface of Agfa Portriga Rapid 111 (glossy fiber) was so so sweet!