I like block. I always have. Even when tanks were stacking dodge in TBC i stuck with block. Felt like a safer constant than dodging. But, now shield block is on a 20/30 sec CD i dunno. I generally take it as it comes.
Saw some figures that said block rating for trash and dodge rating for bosses was the way to go. Also saw some figures that stated that 2% block was as good as 1% dodge, but it really depends on what is hitting you and how hard :P
The theory behind it was if a mob is only hitting for 1200 a block becomes avoidance and is therefore the same as a dodge..... but you gain rage and as block is easier to stack, less rating to % block, than dodge then it is considered better.
Simple answer is carry 2 sets of gear. Trash set and boss set