I can not really think of a protagonist I have cared about the most, because I do not read a lot because I am picky. But, I can tell you what makes a good protagonist, or just a good character. Readers like to get to know the character they are reading about. They like to know how they would react to certain things, what they look like, how tall or short they are, etc. Being able to connect with a character or get a feel of what the character is like, helps the reader understand the character more and be involved in the book, and what happens to the character. Characters who have personalities are much more interesting and a lot less boring.
The best book that I have ever read is The Outsiders. I really like this book because I enjoy the way that the author has written it, and the way they explain things. I also really like the names the author has chosen for the characters in the book, they draw the reader in, and the names are unique which makes reading it more enjoyable. I like all the excitement in the book and how every character has their own quirks. I like the vibe of the world they live in and I like the way each character handles things. I like how the book has lots of funny, happy, sad, and excited moments in the book which helps the reader relate to it more.