Unfortunately, it really does matter what you're going to be hunting, because the top of the line armor sets are going to be more expensive than they're worth if you're fighting something small.
The key is being economical. When you get hit, a piece of your armor takes some of the damage dealt, and it loses a certain amount of value. However the damage of the hit can never be lower than 1. So, if a cheap piece of armor can do the job, it's going to be better than an expensive set of armor which will do the job equally well, but will cost much more for every hit it takes.
That being said, here are some of the top of the line armors:
Best not-unique: Carramone
http://www.entropiawiki.com/Info.aspx?chart=Armor&name=Carramone
Best armor period (but is unique): Unique Lady (or Lord) Kraster
http://www.entropiawiki.com/Info.aspx?chart=Armor&name=Unique_Lady_Kraster
http://www.entropiawiki.com/Info.aspx?chart=Armor&name=Unique_Lord_Kraster
These provide the most total damage prevention.