Wow...I can't decide on the characters! The iD L ones are all pretty cute, but the 15th anniversary has all the Ura characters. I'm going to say I'm tied on characters. I love them all!!
I love both, even though I don't have the 15th Anniversary (getting it for my birthday though!). I am incredibly excited about the release of the Princess Spacy, which I preordered ages ago. I am currently running my normal iD L, which I LOVE!
I have the Royal Purple version of the 15th Anniversary edition. In my opinion, there's several more characters that I love in this version than the original iD L, which is why I decided to purchase the 15th Anniversary. It also has Mimitchi. Her sprite is so cute in color. ^_^