_Calculus Made Easy_ by Thompson (now in a new edition revised by Martin Gardner) was a former classic used by all sorts of people, and Feynman learned calculus from _Calculus for the Practical Man_, which was hardly sophisticated by modern standards. As long as you stick to a book some sizeable number of people think is okay, I don't think it matters that much what you learn from; the important thing is that you work through theorems carefully enough that you really understand them. Whether it's Spivak or Velleman or Thompson or OpenStax or Stewart (only for those who are assigned it, since otherwise there's no reason to spend >=$100 on it—it's not worth the premium) or Ross (his _Elementary Analysis_ book), worry about learning the concepts more than worrying about which book you chose. You can always refer to alternative books or youtube videos if a concept isn't clear in the primary book you chose.

Others have already mentioned the classics, but if you're looking for something more off the beaten path, you can check out my book: No Bullshit Guide to Math & Physics which covers calculus in approx. 150 pages (Chapter 5).

You can see an extended preview of it here: https://minireference.com/static/excerpts/noBSmathphys_v5_pr...

And a standalone concept map here: https://minireference.com/static/conceptmaps/math_and_physic... (bottom of the page)

Check out the reviews on amazon if you're interested. It hasn't been adopted as the main textbook at any university yet, but many teachers recommend it as supplemental reading for their courses.

I, for one, couldn't find a better one at the time I've read it. There are a lot of crappy ones, on the other hand. You are right in affirming that this is a massive investment.

Depends enormously on your level and willingness and dedication. At that level the best ones are Spivak, Apostol, Fichtenholtz, Kudryavtsev.

I self-taught from an early edition of Stewart and loved it.