ANA has the best redemption value for EVA flights between the US and Taiwan. 95k miles for business class roundtrip compared to 150k+ on EVA's own program. Availability can be scarce but if you're only looking to get one ticket every year or two then it should be manageable.

ANA is an Amex transfer partner (in the US) so you could look into Amex cards.

PE at 120k miles is not really a good value. A roundtrip PE ticket is what, like $1500 - $2000? So you're getting around 1.5 cents per mile. If you get 2 miles per dollar with the Citi Double Cash card then that's a 3% return - not a huge difference over 2% cashback and much less flexibility.

I wouldn't bother with the Taiwan credit cards if you are based in the US, since they all have foreign transaction fees that would eat into your returns, and they are also constantly changing their rewards structures (at least compared to US cards). Sign up bonuses are low, annual fees are high, and most of the benefits are geared toward local spending. For example the EVA Amex Platinum has a $1200 annual fee and the base earning is 1.1x points per dollar, so, yeah...