I believe that the type of wire that is used to install the service in your house all depends upon what the Prem Tech wants to use.  If you ask me Ethernet is the best option since... let's face it, Ethernet is built for data.  The Coax solution is ok if that's all you can use but if at all possible use Ethernet.

Ethernet is far less susceptible to weird issues whereas the Coax solution is very finicky about the quality of the cable, the quality of the connectors, and the quality of the splitters used in the setup.  Ethernet, tried and true technology for data transfer.

I have no scientific proof but I'd have to say that the majority of bad uVerse installs and system issues are caused by bad coax whereas we hardly ever see any issues with Ethernet installations.