I attended Holland vs Morocco in 1994 in Orlando. Still the best sporting event I have ever attended live. The sea of 60,000 people in orange chanting and singing could be heard over a mile away. The passion and excitement was amazing and will forever be etched in my mind.
Even though it is not professional my second best live sporting event experience has been NCAA tournament 1st and 2nd round games. Awesome excitement and energy, plus back-to-back games is tons of fun.