How should I evaluate the suitability of acquired equipment in Diablo 3?
I am having trouble figuring out which equipment is worth using when playing the main story line of D3.
I found a shield for my Crusader character which looks much better than the one I was using: the rating is higher (714 vs 547), also the Block Amount is much higher (948-1088 vs 392-543). It also has a marginally higher chance to block.
However, the game shows me that both my Toughness and Recovery will both be diminished after equipping the new item (by -12.1% and -17.2%, respectively).
I often find myself in a situation when the rating and the raw stats of an item look like an improvement, but the stat changes calculated by the game show a (sometimes hefty) decrease.
What is the cause of the (apparent) discrepancy, and which set of values should I trust. Should I equip the shield or not?
TLDR: keep the rare shield, it's better.
First of all, you Rare shield has 6 magic properties, while Magic shield - only 2. Now let's put all bonuses into 3 categories:
Rare shield Magic shield In-game Diff Damage +188 Strength; +10% Condemn Damage +235 Strength +1.2% Toughness 547 Armor, 13% Block, 543 Block, 29 Arcans Res, 58 All Res 714 Armor, 17% Block, 1088 Block -12.1% Recovery 44 Life per Wrath Spent +1303 Potion Heal -17.2%
Damage: The magic shield gives more Strength, but in-game calculation doesn't take into consideration +% Skill Damage (because you may not be using this skill). If you are using Condemn, then Rare shield is better in all 3 categories.
Toughness: The rare shield provides less regular protection (armor, block chance and amount), but has nice resistance bonuses, especially +58 to All Resistances. There is a popular belief that each point of All Resistances is roughly equivalent to 10 Armor points (for example, see this https://eu.forums.blizzard.com/en/d3/t/armour-vs-resistance/2549 discussion). So the rare shield has effectively extra +580 Armor, that's why it beats the Magic one in this category.
Recovery: This one is very subjective, but it feels like "Health per Wrath spent" is more useful, because you are using skills all the time and will have a constant healing with this bonus. Looks like the game calculates it similarly.
So looks like the Magic shield beats the Rare one only in terms of damage and only if you are not using Condemn, but even this 1.2% bonus seems insignificant.
I recommend you search for some other Rare shields of higher level. You can visit blacksmith Haedrig and ask him to craft one.