Fiber is fragile, does not like bends, requires skill and equipment to terminate and test, and is expensive. We used it in large data centers for Gig-E and higher. Also handy in very noisy, and I mean VERY noisy environments. We use it for security reasons as you can't inductively tap it. If running fiber, then you have the added expense and failure modes of fiber to copper transceivers. Fiber transmitters and receivers are more failure prone than copper. Do not forget all fiber is not the same. Multi-mode or single mode? For the specific layer one, how many fibers? Which connectors? Oh, yea, we had more issues with errors from the transceivers than the actual runs.
But for a house? Cat-5. Cat-6 is actually an advertising made up term. 5+ is the same bandwidth but as the pairs are bonded, over long runs ( hundreds of feet) they have a more consistent impedance for Gig-E. Shielded cable is also only useful for long runs in terrible environments or where required for medical certification.
I know there is a lot of talk about errors and noise, "audio" switches etc. But if running Ethernet, you are running TCP/IP which will with the protocol resend the packets until they all get the correct check sums and then deliver them in sequence. Any bit drop or noise goes away in the first three layers of the stack.
IF you have ground loop issues and you have not applied sufficient black magic to fix them, and if you can identify your network in a small domain like a house, then opto-isolators can help. We used them on buss and tag lines back when IBM demanded their CPU to be on a different lines branch from third party. Probably irrelevant in a house.
Your money of course. Don't let audiophile rumor re-posters or armchair "seams reasonable" pontificators who spending your money overshadow reality. Just because something exists does not mean you need it. I am not an expert, but I did have a career in industry and Government in failure analysis, R/W engineering, data systems architecture, SA and SE in life-threat reliability systems so I know a little. I have polished my share of fiber. :)