Its up to you really.
Personaly i'm going more for STR/CON as a warrior, i look at it this way.
CON - HP. Yeah, its not a ton. Currently my 228ish con gives me 350ish HP and 25ish to each resist. As i level up and my con = more HP, it should pay off more.
STR - increases my damage done, therefore increasing my aggro ever so slightly, and also increases block rate *up to a certain amount. 16% i think?*
Dex - increases my parry, up to a certain amount, which i believe was 8%? 12% All i remember is that it was smaller than the max % attainable by STR.
in reality, your going to want all 3 of those attributes pretty high. The more blocks / parries you get, the less mana your healer has to spend keeping you alive. The more HP you have, the more 'even' your health falls, preventing huge damage spikes that healers can't keep up.
Picking attributes in this game is pretty tricky for a tank actually.
int increases hate for taunts, slightly
vit increases your in combat health regen
currently as a lesser giant with 3 str 1 con per level from racial, i'm putting 2 str, 4 con, 4 dex.
As a pally your going to want to consider wis for mana pool, and INT for spell damage as well most likely. Not an easy formula
