So who is Stareks Gage for now? Is it better?

Steraks is unique in that it's the only item that boosts your base AD. Ordinarily, the only way to boost base AD is by naturally leveling up; AD on items or runes doesn't count towards base AD. This makes it excel in two situations.

One, on characters with Total AD scaling. The vast majority of abilities in the game scale only with Bonus AD, but a few scale with Total AD. Those that scale with Total AD get a huge boost from Steraks. You can tell the difference in the tooltip; abilities that scale with Bonus AD will have the AD portion in parenthesis and colored orange - ala, 10(+10). Abilities that scale with Total AD only picture a single number that's colored orange.

Two, on characters that build Trinity Force. The Spellblade proc on Trinity scales with base AD, and can't be enhanced in any way other than by leveling up. Steraks increases your base AD by 50%, and thus increases the damage of Spellblade by 50%. Instead of Triforce dealing 200% of your base AD on hit, it does 300% with Steraks. Iceborn Gauntlet would be boosted from 100% to 150%.

Then there's the shield component. Steraks allows Fighters to survive both burst damage and ambient AoE in teamfights by granting a substantial shield when they've taken enough damage. When it procs, they also gain 30% Tenacity, so CC lasts less time on them.

So, Steraks is good.

It's for divers who build tanky like vi or pantheon or juggernauts who are the Frontline damage dealers like yorick or Darius.

When I play yorick I rush a sheen then build a stareks because it boosts the sheen damage

It's perfect for Sheen users, and is now even better. Before you would just get +30% base AD with an additional +30% with Lifeline And now you just get a +50% base AD, which at first seems like a nerf, but needs to be noted that you don't need Lifeline to proct to use it and remains active at all times. This overall makes it a buff for the item.

In addition now Lifeline for this item gives 30% Tenacity, which is something pretty much every Sheen user wants because all of the melee ranged ones tend to be vulnerable to CC (Yorick, Nasus, Trundle, etc).

So overall the item is buffed and feels so much better.