Like every other anime unless I have no other choices, always, always dubbed. English is my native language and I've always found reading subtitles to be aggravating and distracting...and often inaccurate, which is even more frustrating. The new (well, it's not new anymore I suppose) Pokemon dub has grown on me anyway, and I'm fine with it.
The tv series I watch dubbed, since English is what is most easily available to me, and I am accustomed to the cast. Though I don't mind watching an episode in the original Japanese with English subtitles if it's an important episode that was censored in the international release like The Legend of Miniryu/Dratini.
Now with the movies I frequently watch both subs and dubs. Since the movies are more story-driven I usually want to see it first as it was meant to be viewed in Japanese because often very significant plot content is removed from the US distribution, the first movie is a must viewing in Japanese as an example of this. Almost an entire half an hour is cut from the beginning, and that time spent with Mewtwo and Ai give the movie far more depth. There's more science-fiction and spiritualism in the original film, and the reason for this Mewtwo's creation is poignant.
Generally the Japanese voice actors are also better than the English ones in my opinion. In a typical episode of Pokemon where all of the Pokemon just repeat their names except for Meowth I don't notice this as much. However, since the movies always make rare, legendary or mythical Pokemon a central part of the story they are sometimes portrayed speaking like humans or communicating in our language telepathically. So if a Pokemon is going to deliver significant portions of dialogue then I am much more critical about what their voice sounds like. Sometimes a Pokemon sounds decent in either language like Entei in the third Pokemon movie. His voice in English great, it's a rich, baritone full of authority, yet warm when it needs to be in the interaction with Molly. I have watched and enjoy that movie dubbed. Other pokemon however are not so fortunate. The actor who voices Arceus in the English dub for 12th Pokemon movie is horrible. His voice is shrill and whiney, and all that screaming just makes Arceus sound unhinged. This dub should be avoided at all costs. Maybe there's another dub like Chinese or French where the Arceus is good--but this one ain't.
So the tv show 99% of the time I watch dubbed. The movies split 50-50 for me between sub or dub.
Sub for me! I think I stopped watching the dub around the voice actor switch, which iirc was mid Hoenn saga? Around 2004 or so. I didn't like the new voices at the time, though I do think Sarah Natochenny has really grown to be a great Ash now. Her voice fits so well! Still, sub is my ideal, since I prefer watching anything in its original language (not limited to anime) most of the time.
I grew up watching dub so that’s what I’ve stuck with, though I have just experienced the voice cast switch and can see why many people disliked it. Taken some time to get used to it that’s for sure. I have watched other anime subbed like Naruto and Attack on Titan mostly because the dub voice actors sucked and the Japanese VA do such a terrific job.
I'm in the "grew up with the dub" club. Even though I stopped watching around BW, if I ever went back to it I'd probably go to the dub.
I only watched a couple of the episodes subbed, and I think that was just because a friend of mine wanted me to watch them early. I can't see myself watching subbed because watching dubbed is just something I'm so used to.
I do think there are good anime dubs out there though, I just don't think I'd be picky about it if I watched Pokémon.
I'm in the "grew up with the dub" club since that's how I watched Sinnoh and all the seasons before, exclusively on TV and Pokemon TV. As I've gotten older tho I kinda switched to the sub around mid-XY in a way to avoid spoilers and be able to discuss episodes as they air.
The sub has a lot of benefits, like keeping the original music and not having some of the more awkward dialogue but honestly the English voice acting is horrible. I glanced through a couple Sun and Moon eps the other day and enjoyed all the VAs except Lillie and Lana's so I'm honestly considering just watching Journeys in dub format and then continue with the subs once I run out of dubbed eps once I finally get back home for Christmas.
In the end though, I'm not sure if I'd watch the dub if I hadn't grown up with it. The music and dialogue in the sub is a lot less awkward than the dub imo. (although I do miss the days when they wrote songs especially for the dub, even if they were kinda cringe.)