I'm building a single-player top-down zombie game in Godot and hit the same question. I ended up with auto-attack by default plus a toggle to manual aiming with a small aim assist (around 15 degrees), so the player can switch mid-fight instead of committing to one style. The whistle lure is a nice touch for the stealth route, since noise becomes a tool and not just a risk. In co-op, would each player pick their own aiming mode, or would it be one setting for both?