The Armory is THE Tainan pub. Although nowadays there are a few other good places popping up, The Armory is still the expat pub of choice. It’s not much to look at, but it has a great atmosphere and a real community feel to it that is lacking in the pubs in Taipei and Kaohsiung.
They have a good selection of food and drinks that are all quite reasonably priced. Saturday nights get packed, and there is usually a DJ playing, but don’t get there too early, it doesn’t get going until at least 10pm and stays open (usually) until the sun rises.