This has gone up a notch since FLASHPOINT when Barry passed on the note from Thomas Wayne of the FLASHPOINT universe to Bruce, and probably even more so since THE BUTTON when Barry created an opportunity for Bruce to meet Thomas in person. Even Pre-COIE, though, it was quite strong (though not Superman/Batman level) due to both Bruce and Barry having sidekicks (Dick and Wally) coming of age at the same time, and those sidekicks were themselves best friends growing up.
I think they get along fine as long as they don't bring up politics (which Barry won't, but Ollie sometimes can't help himself).I'm not sure if Barry and Ollie actually dislike each other enough to go in this category or if they eventually got along enough to be friendly acquaintances when hanging with Hal. Buried, what say you?
Buried Alien (The Fastest Post Alive!)