18 Stam should be your priority over 275 health. Kings and other buffs target your stats or a % of your stats, but not things like "adds 60 health". If you have 275 health, even buffed it will be 275 health. Your stam however scales with your buffs from different classes and can drastically effect your final numbers, especially if you have a lot of stat gems slotted.
Goros, If you are ANYTHING but a bear, 275 health is better, mathematically speaking. Even though it doesn't scale, unless your stamina->HP conversion is 15.3 or better, of which only bears qualify (~16 conversion rate). Next closest is probably blood, I'm guessing about 12.2 with 3% from VotW, 10% from Kings and supposed new Frost Presence buff (8% stamina, up from 6%). I hope I haven't missed anything. Paladin tanks drop slightly to 12.1%, New Sacred duty (4% instead of 8%), Combat Expertise 6%, and Kings/Bosanc 10% (yes, I purposely ignored AD's 8.75%, it won't be on your paper doll)
And as stated originally, it's only 13 HP. Srsly.