Olan Soule or Adam West as Batman

On one hand, Olan Soule originated the Batman role and he was arguably, the definitive Batman voice actor prior to Kevin Conroy. Not only did he voice Batman on Superfriends prior to the Legendary Super Powers Show season (1984), he also provided Batman's voice in the 1960s Filmation series.

https://www.handitv.com/stories/the-meek-mayberry-choir-director-became-the-voice-of-batman-for-a-generation

https://13thdimension.com/13-great-things-about-filmations-1968-batman-cartoon/

On the other hand though, you can't really go too wrong by having Adam West voice Batman after famously portraying him in live-action. And West was on his own terms, arguably the definitive live-action Batman actor prior to Michael Keaton. I guess, that it was actually a major coup to bring Adam West. It sort of gave the Superfriends show extra credibility and weight.

https://www.behindthevoiceactors.com/voice-compare/Batman/Batman/

https://www.slashfilm.com/1245904/batman-cartoons-rough-start-animated-series/