I like Jame's guides. If you want a plug-in/add-on and videos to go with the guide then you will likely have to pay for a guide. They aren't really expensive and it's only worth it if you want those extra items, but buyer beware because I know that there was at least one guide that basically took Jame's guide word-for-word up to L60. I consistently read good reviews about Joanna's guide.

As for content, I'd say Jame's guides are better, if not as good as, the others I have seen. I have used both his Alliance and Horde guides to 70. However, since I installed Questhelper I find that it's fairly adequate for my needs.

The main advantage of a guide is to make leveling the most efficient through "multitasking" and reduce time by not running in circles. Guides also indicate those out of the way escort quests and dropped quests (you know the ones that you get a drop and click on it to start a quest). Questhelper does not show dropped quests (AFAIK). They are the easiest quests to do too!

Also, the majority of guides are obviously not written with multiboxing in mind. Of course, that doesn't stop me from using them as I just skip the collection quests I don't have the tolerance for.

At this point I doubt I would pay $ for a guide.