Depending what you consider nightlife. The largest disco is called „Nachtschicht“ and is located in Hard, but it‘s not in walking distance at all (so either designated driver or taxi).
If you can party without disco, e.g. in pubs or restaurants, then Dornbirn is better.
If you are interested in drinking and music, then you can go to Oktoberfest in Hohenems (next city in the South):
https://www.oktoberfest.cc
It‘s Bregenz by the way, not Bengenz.