> One of the interesting things I've noticed is that (around here at least) the over-the-air TV is much higher quality than the local providers (cable and fiber).

There's a substantial difference in bitrate between OTA broadcast (for the main channel) and the cable broadcast. Typical cable will stat-mux several channels down to well below 10 Mbps/channel. Main OTA tends to be around 15 Mbps (for a different encoding) but not stat-muxed. So to some extent, the quality of the channel you're watching on cable/fiber depends on what is going on in the adjacent channels.