As a cleric tank there are a lot of stats that are usefull to you and here I will show you what each stat does assuming you have atleast picked up the basis to tanking spec (see below at tanking builds).
Toughness: Reduces bonus crit damage taken from non player sources. 1Toughness gives a 2% crit bonus reduction.
Endurance: Increases you health by 9 per point. We get a 90% endurance buff from MoL and as a result 1 endurance on your gear will give you 17.1 health.
Wisdom: Increases your spellpower by 0.75 per point and also some mana regeneration.
Intelligence: Increases your spellpower by 0.25 per point, your max mana by 10 per point and your spellcrit by 1 per point
Strength: Increases your Attack power by 0.5 per point, your block and parry by 1 per point.
Dexterity: Increases your Attack power by 0.5 per point and your dodge by 1per point.
Focus/Hit: Increase the chance to hit with spells/melee hits by 0.2% per point. (1 focus also increase hit by 1)
Attack Power: Increases the damage of your melee attack.
Spellpower: Increases the damage of your Spells, gives you 0.9parry per point, 0.6dodge per point and 0.3block per point.
Parry: Increases your chance to parry an attack by 0.01618% per point resulting in 0 damage taken.
Dodge: Increases your chance to dodge an attack by 0.02369% per point
Block: Increase your chance to block an attack by 0.04854% per point and also effects the amount you block for (for blocked amount see diminishing retuns).
Some stats have caps that effect how high the priority of each stats is.
Focus and Hit: 70
Focus and Hit: 120
Focus and Hit: 220
Focus and Hit: 320
Parry: 20% (1236 parry rating)
Dodge: No cap at all.
Block: There is a soft cap at 45% block chance (from rating alone and doesn't affect block from PoR)
Armor: No known cap atm
The stat priority assuming a raid environment (but even in a non raid buffed situation this is the stat order you should gear for)
Toughness (until cap) > Focus (until cap) > Endurance > Strength > block rating > Spellpower > Wisdom > Dexterity > Dodge > Parry > Intelligence
Toughness, focus and block are as a result the stats you should be looking for the most on gear.
For more information regarding stat priority and stat values I advice looking at this thread on the official forums: http://forums.riftgame.com/showthread.php?205793-Justicar-Speadsheet