Best Stag I was ever at was in Liverpool. Hotels ,beer, taxis ,food etc very cheap. Lapdances (it you are so inclined) were £5 and this was before the Euro parity. People there were very friendly and we caught 2 matches there ....LFC on the Saturday and MCFC by train on the Sunday before the late Ryanair Sunday flight home. Stick with the bottled beer though.
Galway imo has its head up its own hole and is to be avoided at all costs. Massively overrated. Sadly you don't even hear Irish being spoken on the streets anymore.