User blog comment:Ravica/Health vs armor/@comment-78.87.90.25-20120128151639

One thing you forgot to mention is that every 1 point of Armor/MR increases for effective health by 1% of your HP. This way the effectiveness of every 1 point of Armor/MR is based on your current HP, and the effectiveness of every 1 point of HP is based on your current Armor/MR.

For example: Tank has 3.000 HP and 100 armor. Against physical dmg he has 6.000 effective life (you can check the armor page). If he bought Giant's Belt (+430HP) he would increase his effective health against phys dmg by 860. Chain Vest+Cloth Armor would increase your Armor buy 63, which would increase your effective health by 1.890. The Belt offers less than half the effective health (for phys dmg) and it costs 110 gold more. Although armor seems way more effective than health at this scenario, it leaves you valnurable to magic dmg, while health would make you more durable against both.

I would suggest you to make a table showing off where is it most cost/slot effective to buy HP or resists and what type of resist. If you want of course.