Beta may have had a slightly better picture, but it wasn't enough to offset its limited recording time of 1 hour vs the 2 hour capacity of VHS. Sure they improved the recording capacity later, at the expense of picture quality, but by then it was too late.

http://www.guardian....5/comment.comment
Later I found out that Betamax had owned the market, but lost it because Sony got one simple decision wrong. It chose to make smaller, neater tapes that lasted for an hour, whereas the VHS manufacturers used basically the same technology with a bulkier tape that lasted two hours. Instead of poring over the sound and picture quality, reviewers could simply have taken the systems home. Their spouses/children/grandparents and everybody else would quickly have told them the truth. "We're going out tonight and I want to record a movie. That Betamax tape is useless: it isn't long enough. Get rid of it."