Before I start I just want to say I will be biased since this show is the one that gotten me into anime and it is very dear to me, I recommend Tokyo Ghoul for the reason of the mental progression of the characters (I am mainly referencing at the MC) and the after effect it can leave on you. For me it was I could feel the pain and loneliness of Kaneki Ken when he first turns into a ghoul and you can see the panic in his face which you can thank the animators for.
You can see what a good friend is through Kaneki's best friend Hideyoshi Nagachika or better known as Hide as he realizes what pain Kaneki is going through and mentally supports him without prying into the his problem, giving him space and time to heal mentality and physically, because for all he knows metal beams fell onto him and a girl he was on a date with after Ken asking the girl (who is called Rize Kamishiro) to the bookstore. Rize died from the incident but her organs were intact so they got transferred to Kaneki's body ,as he was barely alive.
After that he turned into a 1 eyed ghoul (which is rare) and started to mentally decline into a depressed state where he was stuck in a mental box not knowing how to get out, until he met Touka Kirishimaa and joined a café called Anteiku that is run by ghouls who are interested in humans and how they can fit into society and instead of killing and eating humans, they eat humans that have committed seppuku (you probably get what I mean I'm just not that comfortable typing the word out so I put it in a Japanese way I guess).

The way they animated it from the manga was perfect since it embodies the feel and tone the manga gives off also the animation is just... AMAZING I can't complain about it in any way shape or form its just a perfect representation of the manga (even though in my opionion it still is better). The voice actors are phenomenal in there field of work (I am talking about the English version instead of the Japanese since I've only watched it in English but I have heard good things about the Japanese voice actors) so there is no reason not to watch it. I have forgotten to talk about the plot but it has been executed perfectly thanks to the director Shuhei Morita who has also worked on the very successful short film 'Possessions' in 2013 before he worked on Tokyo Ghoul in 2014 which is now his most famed work in his career and rightly so.

If you want to get a friend into anime or you want to yourself I Highly recommend Tokyo Ghoul as the first one you watch or if you haven't watched it you should watch the amazing work of Sui Ishida. If you have read all of this I just want to say Thank You since this is my first review so sorry if I rambled on a little bit.