On one hand, you don't actually need to finish watching The☆Headmasters to watch Masterforce and/or Victory. Each series is relatively self-contained enough that knowledge of their predecessors isn't essential (although watching Victory first does reveal and end spoiler for Masterforce). Having said that, after you watch Masterforce and Victory, you're probably not going to want to go back and finish watching The☆Headmasters.
I personally don't mind The Headmasters so much. IMO, The Rebirth was a poor execution of what was originally a better concept, whereas The☆Headmasters was a better execution of a fairly ordinary concept. Although Sixshot has a pretty cool personal arc in The☆Headmasters.
--------------------------------------------
*Season 3's Daniel/Wheelie are like Jar Jar Binks in Episode I, whereas in The Headmasters they're more like Jar Jar in Episode II.![]()