I bought my Betamax in the store having compared VHS to Beta side by side. When I say that Beta was better the main thing I'm referring to is the clarity during fast forwarding or reversing. When scanning through a video VHS was full of staticky noise, but Beta was clean. I don't recall that the quality during regular playback was particularly different, but I like to be able to see what's happening when I move around a video.
It seems like a clear winner. Of course, this was comparing one particular beta machine to one particular VHS machine.