It is between Shin Gouki, Gouken, Oro, Gill, and Shin M. Bison in terms of most powerful, as long as we all accept that Ingrid is a Mary Sue piece of shit who should not, nay, does not exist. It is unclear who is top of those five, but in my personal opinion, Gouki, Gouken, and prolly Oro of the five are strongest.
Gouki, Cammy, Chun-Li, Sagat, Dudley, Balrog those are some of my favorites.
Healthy Gen has not shown enough IMO, and even with hype he does not compare to shit like leveling mountains, splitting oceans, sinking islands, or taking nuclear assaults IMO.
Because of his sickness, and after taking Gouki's Shun Goku Satsu without blinking. That was also in SFA2, and in SFA3 Gen has an ending where he beats (but doesn't kill, of course) Gouki.
In the Udon comic, full strength pre-cancer Gen beat a younger Gouki who hadn't mastered his style yet. They meet again later and lament the situations have reversed, and how grand it would've been for them to face each other at full.
Man, there has been like, one person the Shun Goku Satsu has actually permanently killed. Surviving it is no big deal anymore. And it was not due to power that he survived it, but due to mental clarity, emptying your mind ftw.
Younger Gouki who did not master style yet. Current Gouki can sink islands with punches, kick sunken ships in half while on the bottom of the ocean, fight in volcanos, split Ayers Rock, and can with what is essentially a power-up vape a forest and send a beam into space. The difference between "Young Gouki who has not mastered his style" and current is astronomical.
^ Plus Gouken apparently beat SF4 Gouki, as Ryu isn't taken by Gouki.
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Sakura, her potential is said to be greater than Ryu's the main character and because she's the most popular street fighter female next to Cammy and Chun Li. She will eventually surpass Ryu in the future.
While she's iirc been said to be stronger than Ryu was at her age, it'll still be a decade or so in-plot before she's going to be a major contender IMO.
Gouki and Gouken are roughly equal, and Oro probably is that level too. Those are the top three.
Then it is between Gill and Shin Bison from Alpha 3. I am unsure which one is stronger than which.
Oh, and Ryu has NEVER beaten Bison one on one, in Alpha 3 he was fighting teams of people at once and beating them. He was also killed by Gouki in SF2, not Ryu. IIRC his only victory against Sagat was after a cheap shot when he channeled the Satsui no Hadou after Sagat beat him, though they are rivals, probably being equals. He beat Seth, but who the hell cares? Seth is weak.
The level of power between the God Tiers and top tiers is pretty huge.