I can't just put one movie, because I just love too talk way too much, so I'll list the movies in order from best to worst in my opinion.
Pokemon Ranger and the Temple of the Sea:
-Featured a WIDE variety of my favorite type of pokemon (WATER). I also thought it was funny that Ash saved the day, yet again, even though he couldn't have to do less with the actual plot of the movie.
Pokemon Heroes:
-I like the water race in the beginning, and the water race revival against the mutant fossil pokemon.
Pokemon - Lucario and the Mystery of Mew:
-I just like the Regis a LOT!!!!!! It also had a cool musical theme.
Pokemon - Spell of the Unown:
-It was the first time I ever saw Aipom (my FAV) actively in the Anime series, and it had my favorite legendary.
Pokemon 4Ever - Voice of the Forest:
-I just got really emotional during this movie.
Pokemon 2000 - The Power of One:
-Um, ORANGE ISLANDS!!!!!!!
Pokemon - Destiny Deoxys:
-All I liked were the epic "Rayquaza vs Deoxys" clips.
Pokemon - The First Movie:
-I just saw it again, and it REALLY isn't as appealing as it used to be.
Pokemon - Wish Maker:
-In my opinion, just a god awful movie (sorry to you fans).