Pain of Salvation - What Album do I need?

Hmm... No one is recommending 12:5, which is a very interesting live album. It is semi-acoustic and they do some interesting takes on their material.

Edit: just saw zedowns post.

As for the studio albums, I think TPE is the standout album. I have them in this order:

TPE
Entropia
Remedy Lane
Scarsick
Be
OHBCL
 
I'd say the most accessible album is Remedy Lane, most people's favorite is TPE. The first two albums have a similar sound and feel that is distinct from their later works, so don't be put off if you don't like one album, you may like another. Reading the lyrics with these guys is mandatory no matter what album you start with.

This. My personal favorite is TPE, but not by a wide margin. TPE, Remedy Lane, OHBTCL, and Entropia are all verrrrry close.
 
In order of personal preference:

Entropia
OHBtCL
TPE
Remedy Lane
BE
Scarsick

I'd say the most accessible album is Remedy Lane, most people's favorite is TPE. The first two albums have a similar sound and feel that is distinct from their later works, so don't be put off if you don't like one album, you may like another. Reading the lyrics with these guys is mandatory no matter what album you start with.

This is close to my take. The first 4 are brilliant! Entropia is an easy #1 for me. The next 3 are really close, but I'd bump RL to the 2nd spot. It really depends what you are looking for. Any of the first 4 are fantastic must haves imo. Whatever you do don't go with the new EP Linoleum. Don't do Scarsick next either for that matter.

Todd