Flash can possibly beat modern age supes, but not silver age, no way. Anyway, the strongest hero: Orion while he's empowered by the source (Maybe Hal Jordan while he's empowered by the Entity), and the strongest villain: I want to say COIE Anti Monitor.
i am going with the non-entity answers here.
hero: Thor. i am a fanboy, but this is more than that. marvel is really pushing for him being the top dog right now since they had him kill sentry(even though i personally think it should have taken a Godblast to do so, not just a massive lightning bolt) Silver surfer was made stronger by galactus at the end of the annhilation event, so possibly him. i know they had a 2 scener in chaos war, but all that happened was surfer blasted thor, he shrugged it off and threw his hammer at him and surfer blocked it with his board. but he wasnt trying to fight the surfer he was trying to get his attention. and of course superman and captain marvel(dc) must always be put in these conversations.
villian: well, sentrys dead, emo prime was retconned or something, and darksied is dead(i think). i may have to go with thanos(unless they killed him too, i am currently floating on an aircraft carrier in the middle of the pacific so it is hard to keep up), but that is the easy answer. i will go with owen reece, molecule man, as my final answer here.
or brian michael bendis.
I don't know in which issue he apeared with those powers, but RKT, is... UNBEATEBLE...
There are a lot of threads, and a lot of videos in youtube showing how powerful is this version of Thor, is almost as powerful as the Pre-Retcon-Beyonder, he stoped the Ragnarok...
in no Particular Order
God of God Hercules
Rune King Thor
Superman Prime 1,000,000
White Phoenix of the Crown
DOV Captain Marvel
Classic Doctor Strange
Simone in the STTGL
in no Particular Order
Marquis of Death
Mad Jim Jaspers
Surtur with the twilight sword and eternal flame
Hero: SS, Takion in terms of power set. Spectre is technically a hero but so was god spawn but for generic purposes. Hercules was a brief power up.
Ultimate hero is Solar Man of the Atom
Villian: tons to pick from. Thanos with HOTC or IG, Anti-monitor in CIOE, Mandrakk, Mikaboshi, Emperor Joker, Mad Jim Jaspers, Beyonder/Molecule Man.
1. Dr. Strange
2. Silver Surfer
3. Dr. Manhattan
4. Dr. Fate
6. Captain Marvel
7. Martian Manhunter
9. Captain Atom
1. Emperor Joker
7. Black Adam
Notice how high cosmics like Franklin Richards, Anti-Monitor, or Galactus were not included.
The recent Hickman run of Fantastic Four. One of the later issues, can't remember which one exactly, but future Franklin is awesome.
edit: I think it was from issue 604, actually.
Expanded scan in spoiler block: