We don't have anyone from Eva here. We can't upgrade on most OALs so I sure wouldn't use one for a LONG haul flight.
DL has flights from NRT, SFO and LAX to TPE, FYI. I understand that Eva has a very nice product--if you can upgrade on zed or IDtkt, it might not be a bad idea. They also fly from the west coast, yes? I'd still look at your airline as far as you can go, then take the shortest OAL.