A simple one that can be summarized as "Survival first. Then morality."

Equality is a social construct. It don't actually exist in the universe at any scope whatsoever. The quantum, molecular, biological, ecological, sociological, planetary, and galactic scopes are in a permanent state of disequilibrium as per the second law of thermodynamics. Drawing a border within that entropic flow and defining it as a closed system works... until an unexplored dependency fails.

That process of constantly drawing lines has been civilization's primary activity: "These are the valid social roles/scientific possibilities/moral ranges/emotional perceptions and here's how people fit into them... and here's how to punish those who do not!" Those who define these symbols and convince others to believe in them bestows power to the author... ergo, the phrase AUTHORitarian. Compound this activity over thousands of years with millions of authors, and you don't end up with one agreed upon metric of how to categorize moral structures... what you actually have is an ecosystem of symbol authors vying for larger and larger fan clubs, mostly through conversion, interrogation, humiliation, aggression, and other manifestations of emotional extortion.

However, even within that activity, an implied metric of categorization does exist. It's just unspoken: All moral systems share the exact same threshold for synthesis. Meaning, If moral system X exists as a response to, and in opposition of Y, then it's threshold is at Y and Y-like things. The moral system will only synthesize with similar symbols. Take the moral system of humanism, which is the preference of the material concerns of humanity over symbols and spirituality. Here is a system that exists to defy symbols themselves as if they are proudly above symbols, yet, even this system generates and relies upon symbols. (Potential value of human contribution is absolutely measured in the symbolism of socioemotional hand-waving and/or GDP projection)

By establishing that all moral systems are just a frameworks of symbols seeking similar symbols and avoid dissimilar symbols, all you are actually explaining is the public interfaces of competing systems. Christians and their social justice derivatives use guilt, Islam and ancestor worship uses tribal identity, capitalists use greed and ambition... they are just different interfaces for moral systems that scoop up people who are already culturally, emotionally, and/or neurologically predisposed to find certain interfaces of morality easier to use than others. (Think of operating system preference with low-information consumers) And since we are now talking about human participation, we are now actually talking about power, which is what these symbol systems are all about: material domination.

Therefore, when discussing any moral systems and their efficacy, we can simplify the question to be "Which symbol system gathers the most amount of stupid people to do the author's bidding?" And I find that question to be totally pointless because no symbol system actually promises survival within the material domain... only domination of it on behalf of the author and associated scribes. Not even environmentalism is exempt because it fixates on ecoconservation, which means nothing in the face of light-speed blackholes ramming into your planet.

Therefore, until someone solves the question of survival in a meaningful way, all moral systems are just masturbatory political revenge fantasies, which discredits all of them for all time. I see no problem with making it easier for people to survive since they exist on a planet consumed with symbol conflict and their petulant authors, floating about in a universe that is ultimately ambivalent about their presence to begin with. If I had any spiritual authority, I would expend all of it with a simple message, "You and your ancestors are forgiven. Just try better this time."