That's the problem with researching, many times the more you read the more confused you will become.
Just as with all things in this hobby, the best conditioner for your system can only really be chosen by you. Others can tell you what worked for them, but system synergy and personal musical taste vary so much that no one can tell you what will work best for you.
My reco would be to search the classifieds, and be patient. When you see a good deal on a unit that intrigues you, buy it and try it. If you like it, you're done, if not, try another.
One thing I would suggest on researching is to find out what the PLC does, and what you want. For instance, you have the RSA and the Walker listed together under passive conditioners. While they technically are both passive, the RSA offers surge protection while the Walker does not. This may or may not mean something to you.
Cheers,
John