There are lots of anime shows that have interesting plots, well written characters, and amazing animation. Out of all the anime shows that I've seen I think that Code Geass is the best. Code Geass is the best at several different categories.
I've never seen a anime show that has a better plot than Code Geass. The first episode starts off interest and excitement and the show continues to be interesting throughout the seasons. The show's storylines involve brilliant debates between characters. Unlike other shows the heroes aren't completely heroic and the villains aren't pure evil. In fact some characters could be considered both a hero and a villain. Despite all of the questionale acts of justice the show doesn't feel mean spirited. The show is emotional and challenging. It took mutiliple viewings of the show to fully understand it. The more you watch it the smarter the shows seems. It has more complexity and depth than most shows. It has brilliantly written drama, action, and comedy.
Code Geass has lots of characters. Having lots of character often leads to shows being overstuffed and it can make the show hard to follow. Game of Thrones has that problem. Thankfully Code Geass takes advantage of having so many characters by making sure which are primary to the plot as well as which are secondary and minor to the storylines. Almost all of the characters are memorable, likeable, well written, and entertaining. I've never seen a anime show that has so many characters that I love. I would list the characters that stand out, but there are too many to name. Of course Lelouch Lamperouge (Zero) is one of the best anime protagonists of all time, but he's helped out by how great his allies and enemies are. There are a few characters that I'm not fond of, but it's easy to ignore those characters due to how many awesome characters are around.
Animation isn't as important as the other two categories, but the visuals of shows and films add lots of unique charm. Code Geass is the best looking show that I've ever seen. It's more visually impressive than any live action show as well as any animated show. Most of the characters are so visually unique and cool looking. Lelouch looked cool enough in his regular school outfit, but he looks way more awesome when he's dressed as Zero. The characters, costumes, machines, and pretty much everything in this show look spectacular.
This is a small part of the show, but I think that it's worth writing about. Most shows only change the theme song once per season, but Code Geass constantly changed theme song. They did it so often that it's clear that the people who made the show had fun working on it and wanted to make sure that the people that watched the show stayed excited. All of the theme songs are well done. The end credits theme song called Mosiac Kakera is one of the most lovley songs that I've ever heard.
Overall those are the reasons why I love Code Geass. If there is an anime that's better at these categories than Code Geass feel free to mention it in the comments.