Okay I'm looking at all these top rated guides and the things people post and I've come to realize one thing. The majority of MOBAFire seems to have a misconception about how tankiness works in the meta.

People don't buy "tanky items" so they can live longer in a fight.
People buy items that give them enough survivability ALONG with the side benefits that help the team or provide presence.
Items such as warmogs and fon are rare purchases that should rarely be considered.
Rather items such as sunfires, frozen heart, aegis, GA are items that dominate the meta.

Aegis has always been considered for the balanced aura for tanky stats.

However, since m5 has brought up the mass usage of GA, all pro teams have recognized one simple thing about GA as well. It provides just the right amount of tankiness along with a huge amount of presence.
That's precisely the reason why AD casters have been rising and why you have people like Diamondprox who build aegis + ga on Lee sin; because you'll have 2 items that provide just the right amount of tankiness.

Items are bought primarily for the benefits of the items now, rather than the survivability and resistances it gives.

People buy Randuin's for the anti-AD, peel, and stall potential.
People buy Frozen Heart to counter autoattackers and provide presence in a fight
People rush Sunfire's to force good trades on the enemy.

People used to buy items such as Atmogs because the meta revolved around becoming an unkillable meatshield that does a lot of damage.
Since the nerf however the meta has shifted already.
I still don't get why people don't recognize this.
This is exactly the reason why people don't buy Atma's anymore.

So please, stop upvoting guides that still advocate such ideas because they are outdated and belong to the old meta. Rather look to the guides that actually balance out presence with survivability.