These are the best manga I've read/am reading so far. All of them come highly recommended. I've provided the genres and why I recommend them so you can decide for yourself if it's your thing.
Manga aimed toward an older audience.
I bought these from Amazon, Ebay, and so on.
Not in any particular order, except for maybe the first two. Lots of hidden gems in here! Thanks for looking.
Manga I will always recommend
Personal favorites. I should read better quality stuff.