The most common calculus standard in US universities. More theoretical than Thomas, heavier on proofs in the later chapters. Problem sets are well-graded by difficulty. The 8th and 9th editions changed problem numbering - check your instructor's syllabus before buying a used copy. Full edition guide: whitepdf.com
Actively unhelpful. The examples provided, and the practice problems selected do not help you actually understand the material meaningfully. If this is your textbook, expect to be doing a lot of outside study.