so funny story, i actually did a project on this for my statistics class when i was in high school, testing to see if people generally preferred tap water or bottled water! the area we were at had very clean tap water, which does of course make the data not quite generalizeable since no one had real reason to be skeptical about the water's quality there. but we first asked people their opinion in general (most people favored bottled water), and then did a blind taste test where they sampled from two cups of water without knowing which one had tap and which one had bottled. turned out that people really couldnt tell the difference between the two despite a general bias towards preferring bottled water :D

dorky anecdotes aside, i personally prefer bottled water if i dont have access to a water filter for the tap, but thats because i still insist i can taste a difference... filtered water just tastes more clean to me (maybe a placebo effect, i ought to have a friend test me sometime)