What's the best proof writing textbook? I'm currently hesitating between buying the following:
-A Transition to Advanced Mathematics by Smith, Eggen, Andre
-Mathematical Proofs: A Transition to Advanced Mathematics by Chartrand, Polimeni, Zhang
-Book of Proof by Hammack
-How to Prove It by Velleman
-How to Read and Do Proofs by Solow

I know I can get PDFs of them for free online but I'd like to know to which one I should devote most of my time/focus on.