How are we to tell what the best analysis of well-being is? Is there any formal procedure (or, more plausibly, heuristic) we might appeal to in order to decide between rival theories? For example, to decide what is just, one might appeal to decisions made behind a 'veil of ignorance', which ensures impartiality. For moral questions, we might consider an 'ideal observer', who is impartial, benevolent and fully-informed. (I suppose this is the ivory tower equivalent of "What Would Jesus Do?") All these methods remain controversial, but they at least provide some sort of starting point. Where should we start when considering questions of well-being?
A natural starting point might be to ask us what we most want. It seems obvious that we are better off (ceteris paribus) feeling pleasure rather than pain. But why is this? What do the various pleasures we experience all have in common that makes them good? It seems the only common feature is our preference; pleasures are those experiential qualities that we like to feel, and pains are ones that we dislike. In other words, the value of pleasure is grounded in our preference for it. But of course we can want things other than pleasure; we also have desires about the external world. So this line of thought leads naturally to a desire-fulfillment theory of welfare. We are well-off to the extent that the world is the way we want it to be.
Alternatively, we might ask what our 'idealized' self would want. This is a better procedure, since it is more plausible to take such an idealized figure as authoritative. Also, this method is more indirect (the previous suggestion was indistinguishable from a substantive desire theory). I've previously argued that this formal procedure would yield actual desire theory as its substantive result, but this is, at least, debatable.
Note that both options so far have been 'first person' -- they have taken the perspectives of the self (whether actual or idealized) as indicative of one's best interests. But perhaps this is a mistake. It seems that third-person perspectives yield very different results. This is because first-person perspectives run the risk of conflating what is "good to" and "good for" a person. Because we can value things other than our own well-being, it might be that we value something as good 'to' us (e.g. the welfare of others), even when it is not good 'for' us in particular. A third person perspective (i.e. a partial variant on the 'ideal observer') might avoid these problems by focusing particularly on what is best for the person, if they have a more single-minded concern for the person's well-being.
That last consideration leads me to think that perhaps the best indicator of well-being is what someone who loves us would want for us. Kids want all sorts of crazy things, but parents are more specifically concerned with their children's well-being. Of course, parents are often irrational or misinformed, so we should 'idealize' them in the usual ways. But the general idea here strikes me as heading in the right direction.
So, if we accept this as our formal procedure, what substantive results follow? 'Pleasure machine' considerations surely rule out hedonism right away. (Surely no good parent would want to hook their child up to a Matrix-style pleasure machine at the cost of their living a real life.) So that leaves veridical enjoyment, desire-fulfillment, or perfectionist 'objective list' theories. Can we narrow it down any further?
Objective list theories suggest that certain things (e.g. knowledge, friendship, achievement, etc.) - and only those things - are good for us, no matter our personal preferences. This seems implausible. A loving observer should want us to achieve our goals in life, whatever they may be. A paternalistic imposition of some 'objective list' of values seems inconsistent with a love that entails respect for a person and their chosen goals in life. Paternalism towards children is justified (from the perspective of their own welfare) insofar as it will help shape their character in such a way as to help them realise their later goals and generally enjoy life.
So I think it comes down to desire vs. enjoyment theories. These are very similar in any case. The core difference is that desire theories say you are made better off if your desire is fulfilled, even if you never become aware of it. Does the third-person perspective support this result? I'm not sure. I'm growing more sympathetic to Kagan's life/person distinction, and so am inclined to say that unknown successes do not make a person better off, because they do not impact upon that person. However, a loving observer might be broadly sympathetic to a person's goals, and thus wish them success in life, and not merely in their person. As such, I think this method is most supportive of a desire-fulfillment theory of well-being.