[jstx1]

Elements of Statistical learning is from the same authors (mostly) as ISLR but it's longer and goes a bit deeper on the theory. Also, Computer Age Statistical Inference which is newer and covers more material.

Other big titles - Pattern Recognition and Machine Learning (Bishop), Machine Learning: A Probabilistic Perspective (Murphy) - these last two weren't for me but different people respond to different approaches so check them out especially if the first two books don't click for you.

[wodenokoto]

> Also, Computer Age Statistical Inference which is newer and covers more material.

isn't that more a history of modern statistics than an actual statistics textbook?

[jstx1]

Not at all, take a look - https://hastie.su.domains/CASI_files/PDF/casi.pdf