I was in UA's lounge and TG's lounge a few times over the last couple of weeks. Showered and ate in both. Beer is better (marginally) in UA as is the shower (although I like the lightness and openness of the shower better in TG's (there is only 1), UA has the combined toilet for more efficient use of time).

Overall I like TG better:

less crowded (read virtually empty)/quieter at typical UA/AC departure times
more extensive newspaper selection
much better (for my taste) food selection with tasty Asian cuisine

Both lounges have friendly and helpful staff, free WIFI etc and I would go to either one but TG is one of my favorite Star Alliance lounges. I feel very comfortable there. There are lots of plug ins in the floor for your laptop if you need power.

Neither has a great selection of hard liquor or printing facilities. If you need something done quickly go to the free internet (but fairly cheap printing) area near gate 23! I printed some e-check in boarding passes for onward flights printed there that couldn't be done in HKG.^