Historically, a common variant of Utilitarianism has been negative leaning utilitarianism, which emphasizes the reduction of suffering as the primary moral concern. While laudable as an ideal at first glance, it runs into the issue that some of its prescriptions end up being counterintuitive. In particular, it would suggest that if it were possible to euthanize all sentient life in the universe immediately and painlessly, that this would be right. I posit that the opposite, little considered variant of positive leaning utilitarianism has some interesting properties that could make it a useful alternative framework to either classical total utilitarianism, or negative leaning utilitarianism, and that its drawbacks are less meaningful than they may first appear.
The idea of positive leaning utilitarianism is simply that we should count happiness as utility, and rather than counting suffering as disutility with equal or greater weight, set it as being of zero utility intrinsically. This at first glance may worry people who wonder if that then allows arbitrarily high magnitudes of suffering to be acceptable. However, this is a misunderstanding of what the focus on happiness entails. Suffering is still bad, and in fact, all suffering under this paradigm is equally undesirable, because it is the absence of happiness at any given moment in time. If we truly seek to maximize happiness, we will want to minimize suffering implicitly, not just because memories of suffering reduce happiness proportional to the degree, but also because of the inherent opportunity cost of suffering.
In this way, much of the intuitive features of suffering focused ethics, like the badness of factory farming are preserved, not because those lives are not worth living, but that relatively speaking, they are not as good lives as could be lived. We can imagine a world where the resources that go into factory farming are better utilized to create more valuable lives in some different arrangement.
On the other hand, no life is intrinsically not worth living at all under positive leaning utilitarianism. There may be better lives, but the idea that no life at all is better no longer follows. In this way, positive leaning utilitarianism is life affirming and existentialist in nature. As long as there is the possibility in practice of some future happiness, it encourages people to keep on living and aspiring to ever better experiences.
A problem of negative leaning utilitarianism is that as a final goal the elimination of suffering at best is neutral with regards to positive worlds. Assuming we can eliminate all suffering and people exist in various shades of happiness, there is no determination about what arrangement of happiness is better. Conversely, positive leaning utilitarianism as an optimization goal says much more about what should be.
In practice, most forms of utilitarianism will function similarly. But only positive leaning utilitarianism avoids the possible failure case of deciding that it is better for the universe not to exist. It does so by being strictly about what is valuable, what it is for, rather than what it is against. In so doing it defends our intuitions about the value of life and positive conscious experiences.
Some may still argue that positive leaning utilitarianism allows too much suffering. But the reality is that we often must endure considerable hardship to achieve the desirable states of reality we want and become happy about. Arguably only positive leaning utilitarianism is willing to say that we should do everything necessary to achieve our dreams, to not give up in the face of adversity and to value our lives as intrinsically worth living, meaningful and valuable no matter what.
Consider two lives, one which is easy and boring, having little suffering or happiness, and one which is hard but interesting, having significant amounts of both suffering and happiness. Classical utilitarianism would be neutral in regards to which life is more valuable. Meanwhile, negative and positive utilitarianism would prefer the former and latter respectively. Intuitively, which life do we consider more meaningful and valuable? The one which has very little in terms of experiences of worth, or the one in which we are faced with difficult challenges that we eventually overcome and lead to greatness, success, and a sense of accomplishment? I would argue that the latter is better, because there are more valuable positive experiences, regardless of the negative experiences that must be endured to reach them. Such lives simply seem richer and more desirable than a life that is comparatively mundane.
Philosophically, this framing of utilitarianism is therefore more robust against destructive notions such as the expendability of lives, and other issues that trouble other forms of utilitarianism, and so I offer it as possible lens through which to consider moral ideas.