Thought this would be fun since I found an old thread ranking the opening chapters. From least to favorite (I had trouble with 2-4; those three could probably be in any order):

7. The Lion, the Witch, the Wardrobe - I feel like the plot wraps up so suddenly here. When I re-read this book, I'm taken back by how short this one seems. It's disconcerting thinking of the children being forced to go through puberty a second time, but I do like the conversation with the Professor.

6. The Last Battle - I think this is inevitable because any attempt to describe eternity in human terms is going to fall far short of the reality. Lewis seems to recognize this by not describing anything that happens after Aslan sheds his lion form. But nonetheless, any human understanding of the eternal state is going to run into the thought of "is this all there is, forever?", and that's scary.

Aside from that, the reunion of all the characters is touching. I wish Doctor Cornelius would have been mentioned (kind of odd to mention Glenstorm but not him) but obviously we know he's there.

5. Prince Caspian - My favorite part of the book (Aslan's liberation of Beruna) comes just before the end, which doesn't count. Aslan's statement to Caspian about the pride and shame of being human is one of the best lines in the series. I do like the ending, but like LWW, I feel like Prince Caspian wraps up a little too fast. It does end with a funny line about Edmund leaving his flashlight in Narnia. We know the kids will probably have a hungry train ride because they already ate their sandwiches at the beginning of the book.

4. Voyage of the Dawn Treader - I like the way Lewis builds to the end over the last few chapters. Things gradually get stranger and stranger after leaving Ramandu's island. The final meeting with Aslan is meaningful, but short. I'm pretty sure this is the book where we see the least of Aslan, which is kind of weird because Aslan is my favorite character and this is possibly my favorite of the books overall.

3. The Horse and His Boy - This is one of the most humorous ending of all of them (Rabadash the Ridiculous), and we get to see the humanity of Lune. Maybe because this is one of only two books that doesn't end with a human character being sent back to Earth, there's more room for Lewis to expand on what happened next to the characters, and it's cool to hear all of it (especially about Corin's boxing career). Interestingly, the timeline suggests that Cor doesn't live to be that old, but that's not borne out in the actual text of the book. 

2. Silver Chair - This has to be the most bittersweet ending. They leave amidst mourning, and Jill is the only child who ever asks to leave Narnia. It seems Jill had a short and somewhat unhappy life. I love how Lewis handles the death of Caspian, with Aslan and the bloody paw. And seeing the bullies and headmistress at Experiment House get what they deserve is downright satisfying.

I do think Lewis wasn't sure quite how to wrap up the book because him ending the book on "remember to visit the caves" feels kind of odd, and part of that might be knowing that Narnia will exist less than 200 more years after this book concludes, so there's not going to be a lot of time to see them anyway.

1. The Magician's Nephew - This has to be the happiest ending of the series - everything is sewn up neatly. I still want to tear up a little when Digory's mother is healed - it's been said Lewis gave himself the happy ending he never got. This book also ends with the hope of all of Narnia's history ahead of it.