I'm from the US, but I prefer the BR lounges, unless there is crowding. The BR lounges have better drinks (in particular, the scotch selection) and the ice cream is a nice treat.
In general, western food in Taiwan is not up to par, and both of the lounges suffer in this regard. But the Taiwanese food in the BR lounges is fine. The SQ lounge is also fine if the BR lounges are crowded.
Both of them are on par or better than ICN/SIN/NRT so you will be fine with wherever you end up. And it's easy to hop between them since they are right next to each other.