[Late reply...but I saw this, and I wanted to write at least something. >>]
Yeah, I'd seen when they started re-releasing them, but I'm not sure what happened with that. (I heard somewhere awhile back they'd stopped.) Though to be honest, I did like the original covers more. (One of the things I loved about the Animorph series was the covers and artwork, particularly ones featuring the aliens.)
This is also one my favorite series from my childhood. I think I started reading the books from our school library when I was in second grade or so, and I read a few of them over and over before i started getting them from the public library we usually went to.
Like I think someone else on here said, I did love the books as a kid, but reading them again as an adult, you realize there are so many deeper themes running throughout the stories that you didn't notice.
The ghostwriter thing--reading the series again now, I don't remember having a problem with that. Every single one of the stories seemed good to me, though maybe if I went back and did some close analysis, I'd see some differences in writing style. However, I agree with those that said the Chronicles were definitely a step above--The Andalite Chronicles might be my favorite book of any of the series, though The Hork Bajir Chronicles were very good too, as was 'Visser.'
As for my favorite books of the series...I'm not sure, most of them would probably be from Rachel's POV, since she was my favorite character when I was younger. (Definitely The Separation would be near the top, and The Reaction. From my more recent reading through of the series, I would also have to put The Return on there. I'm pretty sure when I first read the book, I wasn't really fully appreciating the events and mental struggle going on there. Also, again, this wasn't one of my favorites when I was younger, but I thought The Change was just incredible, in the moral questions it grappled with. The Yeerks are set up to be pure evil, and so learning more about them as individuals and seeing how their culture has affected them while also seeing how they each have their own separate views really gives the series a greater sense of depth.)
“After all, absolutely no one can help but suspect a criminal, liar, and manipulator of committing crimes, lying, and manipulating. And of course, no one is more aware of that simple fact than Artemis Fowl.”
Opal sets into motion her most diabolical scheme yet, to frame Artemis and turn his closest friends against him. Only this time she has a new calculating partner who knows Artemis better than he knows himself. [An Artemis Fowl fanfiction, set after The Atlantic Complex.]
...Shameless self-advertising, guys! C;
(And if you're really bored: AF fanart. ;J)