Oh good, we can get this out of the way immediately:
Regarding subs/dubs/nothing - I prefer subtitles. My Japanese isn't good enough to be able to just watch without subs yet, but hopefully someday. When I watch in Japanese theaters (we don't do TV), of course there are no subtitles, but it is fun to force the brain into that "desperation" mode which I think helps with increasing listening comprehension. And context is still King.
My opinion on dubs is that, for the most part, dubbing invariably fails to capture the original voice actor's performance, loses lots in translation, and inevitably results in a skewed experience of the anime. But the worst problem, in my opinion, is that there are simply things that are said in Japanese that make sense in that language/cultural medium, that no English speaker would ever say or possibly even think, at least not naturally. So it is jarring to me to hear English saying the things being said, while it does not jar me to hear it in Japanese and read it simultaneously. Add to this that, generally, dubbing performances in English (even the best Ghibli titles) are not very good or anywhere near the quality of the original voice actors, and that is why I prefer subtitles. Having worked a little on dubbing for live action movies in the past, I am familiar with the script translation difficulties involved, and the desire to match the english to the lip movements given the assumption that English-speakers will not watch something that isn't lip-synced. Personally, the more familiar I become with Japanese and the culture, the less I appreciate these attempts to do dynamic-equivalence translations (i.e. Neil Gaiman's script for Mononoke Hime). And when a character strings together a ridiculous English sentence with bizarre pauses just to match the mouth movements, I find it very distracting knowing how it changes the interpretation of the story as a result. And sometimes the overall choices made have a huge impact on how you view a character, such as Jiji the cat in Kiki's Delivery Service, whose performance in English is drastically different from the character in Japanese.
I am not completely convinced good dubbing is impossible, just exceedingly rare. There are so many factors that need to come together to make an excellent dub, and it seems like no one is capable of doing it right. In an ideal world, with unlimited funds, I would love to assemble a group of talented people to do some dubbing experiments and try to craft a reproducible process that would virtually guarantee excellent dubs. Of course, in my fantasy, I would get to call all the shots and not do any of the actual work, so this isn't likely to ever happen.
Until then, life is short, and I'd rather watch subs any day of the week.
Ok, regarding Manga, I'm still relatively new to the medium. I cannot read Japanese well enough to read manga in the original, so I'm left depending on what I can find online. The only manga I own is Nausicaa, because it is awesome. I have it in English and Japanese as I hope to make it my first manga I read in the original language some day. I also have it in the smaller individual volumes to lend out to people, along with the larger hard bound versions.
Otherwise, I really enjoyed Cross Game on Viz Media's app. It's the only thing there that I ever bought, because I am averse to spending money on things like manga/anime as stand alone purchases, as I'll usually only read/watch something once. The exceptions are the Nausicaa manga mentioned above, and for anime I am a Ghibli movie collector, because I do watch those again and like to use them to introduce people to the best anime has to offer.
Most recently, I have been enjoying Crunchyroll's manga subscription service. There aren't any truly great titles yet, but I am enjoying "A Silent Voice", Arslan, Arpeggio, Japan Sinks, and Silver Nina. There's a lot of manga that is extremely puerile in nature, so it's tough to wade through the junk and find stuff I like. I wish Crunchyroll had some parental controls so I could allow my son to read selected titles without him being able to get to all the other stuff too. I'm pretty sure he'd love Japan Sinks (he's a geology nut), and "A Silent Voice" could give him a much needed lesson in empathy. Ah well, it's still a new service, maybe they'll get around to it.
Well, sorry but the rant, but hopefully that answers your questions!