The first 3 classes Feeder (since you are using a Barbarian), Samurai and then Paladin can use all armor types. Then you are subject to Robes (Monk / Ninja / Warlock) and lastly Headhunter that can not use Heavy armor.
Point is, basically Scales are more versatile with high physical defense and some magical defense. Thus more expensive than plates or chains and more sort after.
Chain over Plate is my preference because of some of the physical and magic defense balance. But I also stat Base int to 30 because I also heal on my characters while melee.
Level 1 to 25 I actually use Stat with +Max Life on my items ... outside of the EE on my weapon(s).
At level 25, I use a 40 strength level 25 (Tier VIII) chain mail up to level 45 when I switch to a +47 Str Scale, all without Enhanced Effect.
At level 60 or 70, I would change to my ML Plate without Enhanced Effect... that is now gone to the Grave, so I will have to resort to my level 45 Plate with 38 Intelligence @ 65+
Everyone is different, and yes I only solo on Hardcore, it is better that you find what works for you, I stat vita to max 100 and int to 30 (if not using my Guardian)
Wish you the best of luck, also remember there have been some good changes to the game.