I'm currently level 20 and playing a Warrior. I'm running with a Reaver/Paladin/Warlord build with Reaver being the main focus. I have a bit more mitigation due to 10% damage reduction through talents. I get no extra mitigation/avoidance through Reaver but I gain AoE threat abilities and some great self heals. I personally like it better then Paladin and Void Knight.
Also Block will only block and portion of damage that you take and is directly associated with the amount of block rating your shield has and how much Strength you have. You can only block attacks from in front of you.
Dodge is pure avoidance, you can dodge attacks from behind and in front and is directly associated with Dexterity and Dodge rating.
Parry is avoidance but not pure avoidance due to the fact that you can ONLY parry attacks coming from in front of you. Directly associated with Strength and Dexterity and Parry rating.
So with this set-up and wanting the most avoidance, Dexterity seems to be the best stat to stack besides Endurance, since it gives you the most amount of avoidance per point(1 Dex:1 Dodge, and 1 Dex:0.4 Parry) Whereas Strength(1 Str:1 Block, and 1 Str:1.5 Parry) now you might be saying "Wouldn't Strength be better for the block?" The answer is actually a no since block is only mitigating a portion of the damage coming at you where dodge is completely nullifying the damage. Of course having a mix of the 2 stats will most likely prove the best since you would get the greatest diversity of avoidance. Also 1 Dodge:+0.024% chance to dodge an attack; 1 Parry:+0.28% chance to parry an attack; 1 Block:~+0.08% Increase chance to block physical attacks and ~+0.23% Increase amount of damage absorbed from blocks.
**SOURCE FOR VALUES** http://rift.zam.com/wiki/Rift_101-_Attributes_%28Rift%29