Shadow Priests! Help!

I got a question from a guildmate who is a Priest of the… shadowy variety. Dealing damage and melting face is not my forte, so I’m hoping someone out there can help. I checked out Fate and Trollin’ as I know they’re both shadow but I couldn’t find their emails to contact them. So alas, I will post an open question on my world.

It’s a question of gear:

[item]Battlecast Hood[/item]
- OR -
[item]Uni-Mind Headdress[/item]

The Battlecast Hood has 2 gems on it: +6 Spell Damage and +5 Spell Penetration / +5 Spell Critical Rating and +5 Spell Penetration.

Let’s assume that there are head enchants on both of them (+22 Spellpower and +14 Spell Hit rating).

I have no idea what to look for in Shadow Priest gear. All I know is crit isn’t valued as highly. Help!