I have seen pretty much every single episode. Other than some of the Hoenn episodes when they were in Slateport City.......or what ever city is after the 2nd gym. I forget. I always seem to miss those episodes. I wish for once that Ash would grow up a little.
The episodes I like the most are: When trainers catch pokemon,gym battles,tournaments,episodes with Legendaries,episodes with champions or Elite 4 members in them and any episode with Team Rocket (Not Jessie,James,and Meowth.) Team Aqua,Team Magma,Team Galatic,and Team Plasma (If Plasmas ever get in the anime.)