Im more familiar with DC side, so the ranking only includes these characters
1 Bart Allen or Savitar( Depends on the version, If were talking about recent version that was absorbing entire Speed Force and easily owning Superman then he would be a rival to Bart)
2 Supergirl, Supergirl's quintillions lines of code feat is insane.
3 Jay Garrick
4 Supergirl(Angel), I dont recall she has some insane speed feats aside from flying to the source wall( Earth to the edge of universe), But it is a travel speed so.......Sorry MrMind 🙁