For books Anabel Hernandez is the best. It's insane how much dirt she dredges up. She goes deep into the corruption and the relationships between the cartels and authorities/government (I started off with Narcoland)
Kilo by Toby muse
Wolf Boys by Dan Slater
El Narco by Ioan Grillo
The Dope by Ben Smith
There are a bunch of decent books out there on top of these
For websites
Borderland Beat has great English coverage and articles on current happenings (This also includes new execution/torture vids as they appear (Pretty every day there are new ones), although they are well indicated if you want to avoid them) and also really good, detailed articles on cartel history
El Blog Del Narco is Spanish but google translate can pretty much get you by. Like Borderland Beat, a mix of current events and history
Narcofootage on Reddit is a good place to lurk. As always there are lots of gore videos but there is more informative content that pops up
There are some fun youtube channels but often their info is inaccurate and they're usually more clickbait commentaries over gore videos.
Kazquillo is probably the best I have seen as he is more directly but he doesn't upload much and his videos can be hit or miss. He doesn't cover gore videos, his best videos cover notable cartel people and gives their history
Youtube isn't the best because good cartel channels tend to get banned. There used to be a lot of awesome content on there. Back in the day, Mexico would sometimes release press interview of cartel bosses they'd captured, and there were a whole bunch of them that got english subtitles but a ton of them got deleted, but there are some that got reuploaded (If you speak Spanish you can still find a lot of these)
If you're interested in clickbaity cartel channels which are fun to watch but often have inaccuracies
Disturbed Reality is one that commentates over gore videos but obviously does not actually show them), but he makes an effort to give out a lot of cartel history while he does it
DeathDoor
WorththeHype
Joshua Roberts (Kind of interesting, he's an American lawyer with a youtube lawyer gimmick but he does have some good videos on notable cartel figures)
Luis Chaparro
Luxury Drop
Max Corrupt
Mexican Archives
Also just wiki is an awesome rabbithole for cartel stuff, I spent hours and hours on their when I first got interested
en.wikipedia.org
en.wikipedia.org
en.wikipedia.org
en.wikipedia.org
en.wikipedia.org
en.wikipedia.org
en.wikipedia.org
en.wikipedia.org
en.wikipedia.org
I don't really listen to podcasts, but there is one called The Underworld Podcast which tells some classic cartel stories (It also covers other criminal orgs)