There are middle ground options if opinion really is split.
We currently have it setup as Hero Slayer mode and a low hero unlock value.
We could try raising the unlock value (score required to unlock the first hero) - possible setting are 0-50, currently at 25.
We could also switch back to highest score gets the Hero.
My preference would be to leave it at 25 points and hero slayer.
Some maps may be ruined by a skilled Hero - but that seems pretty realistic to me especially in the Clone Wars
*edit
There is also the Hero respawn timer - how often a new hero can appear after the current one has fled.