I cook tons. I have ~100 cookbooks, a 1HP meat grinder, a deep fryer, a 75,000 BTU outdoor wok, a mangal, many fermenting vessels, hell a fermenting chamber for koji, and way too many knives. Someone at work asked about cookbook recommendations by country so here it is. There are many omissions to this list. It aims to be "if I wanted to get into X cuisine, what is the first cookbook I should buy to get started'.
General italian - Zuni cafe cookbook is a standout. Everyone says to get a copy of Marcella Hazen's Essential Italian but meh, I reach to zuni cafe way more often. Hightly recommended. Maybe Molto Mario or Babbo for a second or third italian book, but get zuni cafe first.
just pasta: flour + water
thai: the first pok pok cookbook is great (not the drinking food of thailand, not pok pok noodles) and super easy to get into. If that hooks you, Thai Food by Thompson is the bible, but muc harder to approach. Night+Market is also a good second book. (edited)
malaysian/indonesian: cradle of flavour by oseland is A+. So much good stuff in here.
general chinese: every grain of rice by dunlop is encyclopedic and amazing. Start here. I have all of her cookbooks and they are amazing. I haven't found the need to branch out since I still have so much to make.
french: bouchon by keller, can't beat it. So fussy. So many good recipes. Standouts are the bibb lettuce salad. The duck confit with brussel sprouts and mustard cream sauce is like, top five thing I've ever made and so so so easy if you cheat and get your duck confit from oyama sausages at granville island. Just meat: pork and sons.
middle-eastern: Jerusalem by tamimi and ottolenghi is just full of hit after hit after hit. Start here if you have no book in this space.
russian: kachka
japanese: still exploring this space, no strong recommendation
korean: koreatown, though I don't use their regular kimchi recipe (but the donchimi is great)
mexican: No strong recommendation actually. I have 5-6. A few bayless, some dianne kennedy, but I find myself flipping between all of them. No one recommendation.
asian dumplings: Asian Dumplings by Nguyen, despite the ultra generic name, is actually a hardcore dumpling cookbook covering china, japan, korea, the philipines, and india. Super highly recommended actually.
spanish: the new spanish table. The font is terrible but it's full of good gems for traditional spanish food.
random honorable mentions that don't fit into a category: momofuku is a great cookbook. I've cooked easily half of it. Learned so much from it and is solid.
For fermenting vegetables: Ferment For Good is super approachable and full of good ideas.
india/pakistan (not vegetarian): Mangoes and curry leaves by duguid
south indian (vegetarian): vibrant india
bread: artisan bread in five minutes a day, works pretty decently for someone working an 8-5 schedule.
vietnamese: still exploring this space, no strong recommendation.
south american: still exploring this space, no strong recommendation.
german: strudel, noodles, and dumplings by dunk
Some honorable mentions here because they are just so damn good.
absolute must follow standout: ladyandpups. Unbelievably good. Must must must read.
baking - lottie + doof, smitten kitchen
asian (general) - the woks of life