First off, Superman is my favorite hero hands down... but I'm well read in Flash and he's a distant 2nd favorite. For these types of matches, Flash is built to win... that's mostly inapplicable to their comic book lives though. (Flash and Supes are very similar characters - both married, conseratively raised, mostly well-adjusted optimists, family ties, mentors, operate with public approval, etc.)
Anyways, this fight is Flash's 8/10... again the context is a bloodlusted fight where they both know it's coming at "Fight!"
Flash is not only faster that Supes, but has faster acceleration, faster operating speed, and speed-force aura tricks (environment, perception, etc). Flash's high end speed feats, the ones he'd use in this battle, are impossible for Superman because of environmental destruction, acceleration rate, and perception rate. We will never see Superman evac an entire city or build a bridge through super-speed alone. Supes will never time travel or exceed the speed of light to the multitudes Flash did.
Sacrifice is as poor an example as Blitz is. In Sacrifice, Wally didn't know he'd need to ramp up his perceptions, but still was the only one quick enough to catch on... meanwhile the same is true in Blitz, Superman appears as an unaware statue to the devestation caused by Wally and Zoom... but arguably the same excuse, no foreknowledge his perceptions need to be ramped... not so in this battle, where they both know they're fighting.
In Flash #209, Supes KNOWS he has to keep up with Flash and even there speaks to his need to ramp up his perceptions, likewise, Flash speaks to the confidence he has in his superior speed. In The Human Race, the ultimate speedster is necessary to save the planet, but Flash is selected over Supes. In Superman/Flash DC Firsts, Superman admits Wally would leave both him and Jay in the dust if not held back by Abracadabra.
When Supes hears Lois is shot- arguably the most important person to him in the world, where he would never hold back his speed- it takes him several thousand times longer to get to her than it did for Flash to find, carry, and evac 500,000 people. These are totally different magnitudes of operating speed.
Personally, to me there is no question who is faster.
For a victory, Flash has a couple options...
- Vibrations - Already prove he can phase through Supes, but the question is whether it would harm him. Supes has been phased into the JLA table and while he was certainly incapacitated and in great pain... it didn't kill him. So while this attack will work on Supes, it's not the instant-kill it would be for a lot of other heroes.
- IMP - Supes has proven he can "die" to blunt trauma as with Doomsday... and that fight clearly wasn't taking place at Flash-level superspeed (though probably quite fast). Flash could probably get in quite a few serious blows before Supes' perceptions caught up.
- Speed Steal/Boost - Taking Supes' speed and adding it to his own. Probably something he should be doing while doing the other attacks. One poster joked that he could turn Superman into a statue, cover him with a blanket, and come back to kill him after the power drained from his cells. Historically, Wally has be able to do this reliably time and time again... the ONLY place Wally says there's an issue is #209, arguably an excuse to justify a "race"... and technically speaking it's not an issue if this is a bloodlusted fight.
- Speed Force/Time Dump - I don't think the gap in speed is enough that Wally could catch Supes with this... the only possibility is if Supes tries to chase Wally and then he does it ala Savitar/Black Flash... but I like to think that Superman is smarter than that. Then again, if Supes isn't chasing Wally... how can he fight him?
- Time Travel - Ultimately this is Flash's trump card. Flash has been shown to be immune to paradox- meaning, he could go back in time and kill himself, but he'd still exist- however, Superman's recent travels through time as well as the Superman/Batman arc show that he is not. That means Wally can go back and erase Superman.
- Kryptonite - Pop into Bat's cave, take the ring, and come back to rumble.