Boy, is this an MMP I can relate to or what? 
I collect vintage cookbooks as a hobby. I don’t cook from all of them, since a lot of the books that fascinate me sprang from the 1950-1960 obsession with convenience cooking… they’re great fun to read, but I have no intention of ever making ham baked in Dr Pepper, or tuna surprise casserole.
I do use some of my books, though:
Joy of Cooking, (1970s edition): yes, I do have the new edition from the 1990s, but it just doesn’t hold a candle to the original edition. I learned to cook from the two-volume paperback set that’s in my collection, and my mom gave it to me when I moved into residence 12 years ago. I will love it and use it until it finally falls apart (vol 2 is already being held together with a rubber band).
The Breakfast Book by Marion Cunningham: Marion is the furthest thing from food snob - her recipes are simple, homey, and completely unpretentious. I also have a copy of The Supper Book that I use on occasion.
Baking with Julia by Dorie Greenspan: an absolute classic from two of the grand dames of all things baking-related. I have no idea how I lived without this book - it’s so clearly written that even challenges like wedding cakes seem achievable.
Fear of Frying by James Barber: I grew up watching The Urban Peasant on CBC every afternoon after school, so James had as much to do with teaching me to cook as my parents did. This little book is full of sketches and stories and recipes by James (I’ll scan some pages to show off when I get home… it’s undescribably wonderful). James passed away a couple of years ago - he was found sitting at his kitchen table, where he had been reading a book, with a pot of chicken soup simmering on the stovetop. That’s how I’d like to go, when my time comes.
The Perfect Scoop by David Lebovitz: The ice cream book to end all ice cream books (as well as the sorbet book to end all sorbet books, and the gelato book to end all gelato books). His recipe for fresh fig gelato is beyond description.
…and there are probably a half-dozen others that get pulled out every 3-4 months when I realise they’re being neglected, but I’d be here all day if I started listing those too. 
My newest acquisition is Eat Me by Kenny Shopsin. I bought the book a couple of weeks ago after eating at Shopsin’s during my NYC trip… I just had to see if his book would be as random, insane and cheerfully rude as the man himself actually is. Now that I’ve read the book and look back on our visit, I’m completely amazed that we weren’t kicked out (something Kenny does with alarming frequency, apparently).