For me the fondest memories go towards 2004-2005 period, so I would probably lean mostly towards that. Although I definitely would not mind experiencing earlier ones as well, there have been many that would be simply amazing to experience live, such as 2000-2003, and the 90's of course.
That being said though, it is really hard to expect that music always stays same and never changes no matter what. Even in this day, there is plenty of good stuff around, it just takes some dedication to search for it. Never forgetting the classics, and the best of times that went by, but also looking forward, is the best way to go around things in my opinion