which planar book should I buy: Manual, Below, or Above?

[Wednesday Boy]

I liked Manual of the Planes. It didn't have as much detail but it covered a wider base of planar topics. And it had a few planar Paragon Paths that I thought were somewhat interesting.

 

[AbdulAlhazred]

Yeah, I liked MotP. It also covers the 'ABCs' that you want to have in order to understand the whole cosmology. There are a bunch of topics which are of considerable interest for adventurers which aren't really covered in the other books. Beyond that there are a lot of interesting areas that are not discussed in other places or are only glossed over. Plane Above was a pretty good book. Plane Below wasn't bad, but somehow I was still left feeling that the Elemental Chaos wasn't really as clearly explained as I wanted in terms of the overall environment.

Demonomicon is just plain awesome.

 

[DracoSuave]

If you're looking for planar fluff, anything that isn't the original Planescape setting falls short, no matter how nice it seems written.

Pretty much every single interesting thing you could possibly have read in any planar book written since 3rd edition was released is a mere summary of the extensive description and world setting that Planescape provided. It wasn't written as 'a cool place to visit.' It was written with the intent that people actually live there... and answers questions about how and why.

All you need to do is change the names around a bit to fit the 4th ed cosmology. The only thing 4th edition added to 'change things up' was the Raven Queen coup. That's the only bit of 'newness' there.

 

[Jhaelen]

The Plane Above is one of the best book on planes in any edition of D&D.

The Manual of the Planes is very strong, but a little to brief.

The Plane Below is a little meh, especially when compared to the other two.

I actually like The Plane Below best of these three, although The Plane Above is also very good.
Both are designed to be used directly in your game session.

Demonomicon roughly follows the same structure but isn't half as good.

Finally, Underdark also uses this structure and is almost as good as Plane Below.

The MotP gives an overview of the planes that is just too general to be really useful when guiding a session, so it pales by comparison. It's main use lies in preparing for a new adventure, looking for ideas, etc.

So, in my order of preference:
1. Plane Below
2. Underdark
3. Plane Above
4. MotP
5. Demonomicon