In PvP, I'll likely favor Endurance and Crit for heals. My reasoning for Crit in PVP is that a critical heal is more likely to make or break a fight than stronger base heals. If I have 10% crit instead of 10% increased healing, I've found it much more likely than 1 in 10 fights I'll save someone from the brink of death, especially if multiple people are attacking them, when I crit rather than just healing for a little bit more all 10 fights.