I think some people like Tiger more than Leopard because it was the last Apple OS that focused on Aqua Blue.
Back in 2004/2005/2006, when you thought of Macs, you would think of shiny white cool computers with nice blue glossy wallpaper with a little camera for taking pictures in Photo Booth. Owning a nice white shiny Mac would easily make that cute girl at school talk to you.
Does this picture bring back any memories?
Now, fast forward to today. Gone are the days where Macs where shiny white highschool-girl magnets.
Today, we think of Macs as being more "mature" computers with multi-touch, glass, aluminum, cover flow, and all that. Tiger is a perfect example of my previous paragraph, Leopard is a perfect example of this paragraph.
See this picture:
Sorry for the long post, but I guess my point is, some people prefer the glossy white with Aqua Blue era that Apple has permanently let go, in favor of the new Aluminum, multi-touch era.
EDIT: Cassie, liking the return of the purple text 😛