I am not an avid anime watcher. There's about 10 anime shows ive watched from beginning to end that I enjoy. I'll list a few to give an idea.

DBZ is my favorite for nostalgia purposes (in my 30s, grew up on toonami) but Fullmetal brotherhood is my absolute favorite and ive watched it like 5 times.

I liked death note, my hero, Gundam as a kid but haven't watched as an adult, sword art was good at first until the weird incest shit,

I really liked attack on titan and that is what I'm basing my recommendation on. I specifically am looking for something that has a long burning mystery behind everything. That's what initially drew me in on titan.

Once I found out what the mystery was, it was still good but I lost a little interest and for me the last one or two seasons weren't as good

I prefer dub (I know, I know. Basic blah blah blah idc) netflix or hulu preferred but I don't mind signing up for crunchy or some other service if necessary.

I obviously prefer action (called Shonen, yes?) But am open to something else.

I mainly want something with a deep, prolonged mystery.

Edit: I checked out the chart the autobot posted. Gonna check out samurai champloo (sp?) Love hiphop. Demon slayer piqued my interest also. Can someone tell me if either of those have the mystery I'm looking for?