Guys, can you recommend me mangas with a Smart MC? It's okay if it's a male or female prot...

http://www.mangago.me/home/mangalist/626481/
check out stuff like ranker who lives twice

You might have already read it since it’s very popular these days, but the FL in this isekai fits into your description. Cunning and strategist.

http://www.mangago.me/read-manga/the_villainess_lives_twice/

http://www.mangago.me/read-manga/the_villainess_slow_prison_life_began_with_her_broken_engagement/

Tomodachi game

Hi there fujo,
I think you’ve already read most of the titles I’m gonna recommend, but who knows, maybe something might not ring a bell!
Let’s start with something you’ve probably seen:

- Full Metal Alchemist. Pretty sure you know it, but in case somebody who’s approaching to manga is reading this, FMA is one of the milestones you have to read;

- Death Note. Copy of what I wrote before, if you’re not new to the environment you’ll know it, but if you’re a manga freshman and you’re not afraid of uncomfortable morality, big brain battles and VERY gray justice, this is your story;

- Banana Fish. This is, like, a pretty old story, but MC is getting no shtick from anyone. Tissues required;

- Jibaku Shonen Hanako-kun. Now, this might appear as your usual pretty shojo romantic story, but this couldn’t be more misleading than that. True enough, this is a visually gorgeous manga, but MC is one of the best little bitch I’ve read and it’s clear as day there’s something really dark lurking beneath the surface;

- King’s Maker. This is kind of a stretch, because ONE of the two MCs and another heavily present character (even if disguised) are serious big brains, but well...The first MC has room for improvement. Still a very nice story which develops organically, with a good balance between darkness and comedy;

- Id:Invaded #Brake Broken. I seriously recommend watching the anime first (13 episodes, easy catch-up), otherwise none of what you’ll reading would make sense. This is, in fact, the sequel of the original story. Beware, the anime is R-17 rated for good reasons (physical and psychological triggers raining like confetti from episode 3), but if you can deal with it, it’s an amazing story. Not that much cunning going around, but definitely big brain use (both insta-thinking [you’ll get what I mean if you watch] and on the long run);

- Mushishi. This is a very quiet (on the surface) story, just like the plot, it resemble a stroll through the forest. Deep thinking ensured. MC is both street-smart (because reasons), book-smart and emotionally-smart. In his very unique way. Overall might feel long and dragged, but I think this is also one of its beauty. If you don’t mind quiet, slow stories, this is a must;

- Sangatsu no Lion (3-Gatsu no Lion). A seinen with lot of scheming, but not the bad kind (shogi-wise). MC is a very smart but very conflicted guy, and depression getting in the way is not the best thing to deal with. Still, a very heart-warming story, even with all the darkness swinging in. Like Mushishi, this is a corstiol-manga, not an adrenaline one. It will make you sit down and think about your life more than not;

I’m not choosing Yakusoku no Neverland (the promised neverland) nor Vinland Saga because I’m catching up, so I don’t have enough data yet.

Why did I not recommend Attack on Titan (Still a masterpiece tho), Naruto, Bleach, Boku no Hero Academia or D.Gray Man?
‘Cause Eren is a yelling bitch (for the major part of the story. Sure, the plotting variable exists, but you’ll have to go through quite the yapping and the “not again, Eren...goddamit”), Naruto is adorkable but he’s a one track-minded buffoon, Ichigo has no flipping idea of what he’s doing 98% of times, Izuku can’t use his neurons to keep a mothertrucking bone sane to save his life, and Allen is the street-smart, white-haired version of Sora (Kingdom Hearts). I didn’t nominee Fairy Tail because...well...we can all agree Natsu has a heart larger than life, but we can also confirm he’s a brainless jellyfish. Let’s not talk about Haikyuu: one of the greatest sport manga ever drawn, but damn Hinata and Kageyama are illiterate goofs.
All of these stories are great, each for a different reason, don’t get me wrong, but MCs are not the brightest bananas of the bunches, even if we love them with all of our hearts and souls.

Pretty long ramble, I’m aware.
I hope to have been helpful in some way, at least with one title; if not, I’m sorry, I’m sure somebody will come up with something that would spark your interest!

Have a good day ;)