What's Jedi Apprentice? If you talk about Padawans, canon or not, I'm a fan of Jukassa. If you talk about some kind of TV show in which Vader made an appearance, then I didn't watch any of them.
The Jedi Apprentice series is mediocre, at best. I enjoyed the books when I was little, but then when I got a bit older, I started reading the actual novels and discovered that they were so much better.
Are you series? You really think that the Jedi Apprentice books are better than most of the adult Star Wars novels? How many of the novels have you actually read, because I can assure you that the Jedi Apprentice series doesn't even come close to novels such as:
-Labyrinth of Evil
-Cloak of Deception
-The Thrawn Trilogy
-Shatterpoint
-The Cestus Deception
-Dark Rendezvous
-The entire NJO series
-I, Jedi
-The Rogue Squadron series
I could go on, but I think you get my point.
As for Xanatos being your favorite EU villain; to each his own, I guess.
I like the Apprentice series more than NJO or hand of Thrawn. On par with original Thrawn trilogy - that's for me. I like it better than Anderson'books about Exar Kun and Daala, better than "Black Fleet Crisis"...
"Labyrinth of Evil", though, is truly great. My all-time Star Wars fave book is, however, Stover's "Revenge of the Sith".
It's a matter of taste, my friend. I liked the writing, the language was simple, truly, but if I want rich English I might try Dickens, not a Star Wars book. The plots might have been simple, but they entertained myself and really, I liked that the books are small and fast paced without endless babble about politics.
As I said, a matter of taste.