Which level ranges were your favourite? why? and what did you like most about them?
85-90? Pandaria
80-85? several zones
70-80? northrend
60-70? outland
50-60? several zones
45-50? several zones
30-45? several zones
20-30? first pvp open areas
1-20? starting zones
or maybe it was the end game experiences at:
Level 60,
Level 70,
Level 80
Level 85
Level 90