Anakin before joining the Jedi: essentially Luke in SW.
Anakin after joining the Jedi: Luke from SW & TESB with Han’s cockiness and charisma.
Anakin after joining the Sith, but before going full dark side: more reserved like Vader in TESB & ROTJ, minus the sheer ruthlessness.
Something like this.
The concept of existing prequel Anakin isn’t that bad, the problem is in the execution. If he were just self-confident and gung ho and wanted to do his own thing, that would be cool. The problem is that’s buried underneath the bizarre decision to make him a leering weirdo mass murderer before we even get the chance to get attached to him.