I honestly can't say I've watched one I didn't like. All of them were filled with amazing animation, intense action, dark and emotional moments, awesome orchestral scores and the Legendary Pokémon at their best. I feel the first three have a much bigger
weight to them, not only because they were the originals, and that they all had a serious, darker tone, but because they were released in theaters here. Other than the Zekrom and Zoroark movies, we haven't seen theatrical releases since Heroes. I wasn't that into the series when the original five movies came out, and I never realized that the two other ones were in theaters, but I'd die to see a new Pokémon movie in the theater, and I can guarantee there'd be tons of people who'll come out to see it. Japan gets all the cool stuff. :c
Anywho, I would have to say Pokémon Heroes is definitely the most enjoyable for me to watch nowadays because Latias has recently become my favorite Pokémon, and for me, it's basically 70 minutes of Latias being absolutely adorable <3
The Eon duo are among my favorite Pokémon, and this movie was a great way to introduce them. They were portrayed very well (their connections and personalities, Latios' big brother-ness and protectiveness of Latias [yet showing a softer side when
he apologizes to Pikachu], and Latias' ecstatic joy and playfulness toward Ash, all of it's just so adorable <3), and made the movie a whole lot of fun to watch. The backgrounds and environments in the movie were beautiful (the town was based on Venice, Italy, they really did their research for that movie). The background music is great, and I love hearing "Believe in Me" in the beginning.
The plot and lore were good. I honestly didn't see a point in Team Rocket being in this movie, though, as they never interact with Ash and the gang, or interfere with the plot in any other way. Hell, they actually have more involvement in the
dub; they notice that the two antagonists are actually part of Team Rocket, in which they are not in the original Japanese version. Regardless, I do like the Rocket trio and they're always there to deliver some nice comedic moments if not anything else. I really liked the backstory and lore, and the two aforementioned antagonists were alright. The movie had plenty of funny, heartwarming, emotional, and dark moments.
Part of me felt the climax was a little underwhelming in some aspects, but in the end, it was really good, and lead to one of the most emotional moments in the series.
As someone with Latias as his favorite Pokémon, I couldn't ask for a better representation of her in the anime. It was one of many stellar Pokémon movies. I watched it a couple times as a kid, I couldn't resist watching it again recently, and something tells me I'll be watching it quite a few times in the upcoming months. It's the absolute best showcase of Latias being the cutest thing on the planet <3