This question has been removed because it violates the rule on poll-type questions. These poll-type questions do not lend themselves to answers with a firm foundation in sources and research, and the resulting threads usually turn into monsters with enormous speculation and little focussed discussion. “Most”, “least”, "best" and "worst" questions usually lead to vague, subjective, and speculative answers. If you'd like, you may PM /u/caffarelli to have your question considered for an upcoming Tuesday Trivia thread.

Incidentally, our subreddit's 20-year rule would prohibit anything more recent than 1994, just because it is too soon to say what invention from 2000-2010 is most important, as their impact on our daily lives are still being unveiled.