I have a Kindle Voyage, but I only use that at home. When I travel (Sun - Thu) I read on the plane using the Kindle app on my iPhone - that way I only have one device to worry about. The other thing I love is that I can have a Kindle app on all of my PCs (Windows Laptop, Surface Tablet, MacBook Air) and access to my work or pleasure books from pretty much any device.
The other thing that's cool is that when you buy a Kindle book, you can buy the Audible version of that book at a discount and listen to the book if you're not in a position to read. When your device syncs, you can pick up reading where Audible left off and vice versa. Due to the extra expense, I only do this for books for work, not pleasure books.