You could write a book about this question. What would Derrida say, for example? Maybe that we ought to pay more attention to the silence at the heart of concrete being so that it doesn't get filled randomly and harmfully . At the same time, whether work is "better" than leisure seems to be a question that might be more profitably informed from a perspective of practical wisdom and lived experience than whether one is an existentialist, a post-structuralist, or a logical positivist. Work can become a driving obsession associated with a media-created need for attainment, while leisure can be associated with family, wellness, and personal growth. The factors that create a healthy balance between work and leisure go far beyond any theoretical orientation. The relationship between practical and theoretical philosophy, explored in other discussions on this forum, comes into play here. Whatever could be said about this question in the language of post-structuralism, existentialism, or critical theory I leave to others more versed in those fields (whether they are workaholics, lazy gadabouts, or happy well-balanced individuals).

A (n existential-)poststructuralist(ic) theory of, or an approach to, work. As the actor isn't the starting point (or unit) of poststructuralist analysis, but the shifting and the flow of structures is (one).

So my initial idea was: work as a kind of motion, which can be seen as a kind of (partly active-)participating, in the flow. And so—notwithstanding the different concrete forms of work and their structural, effective and subjective situations—work as (at least theoretically or slightly) better than to be (only) worked on/with, as an object of social-systemic and structural forces, (functional) requirements and results and the effects of different actors within that swirl and ongoing flow (of life). The location of the flow in the human way: living as a social creature, nowadays in a societal form of cohabitation. Being embedded (and incorporated in different ways) in societal systems and social structures.

I think work, as in research, is always bettere than playing video games or what not these days. The key, and this is why I break with most (accept Foucault) is to understand what the work is geared for. I really like Foucault's last lecture series Courage to Truth as he is struggling with the problem of cynicism which I think is crucial for folks today to wrestle with as they try to see through the crap in front of them

Partly touching the topic: Roland Barthes' "Comment vivre ensemble?" (cve) is one of my favourite books. (But) it is speaking to and about—empirically (and structurally probably necessarily)—a minority (idiorrhythmicians). The (re)constructions of idiorrhythmic life practice in his cve-lectures seem to me like a small side branch in the margins of the basic flow of life.

The main stream of the ongoings of ("everyday")life is a stream. A flow. So a hypothesis of mine would be, with an existential approach on the basis of a poststructuralist world-perspective:

As we are within this ongoing and evergoing flow, our movements count more than the illusions of essential(ly), fixed things. Therefore work, as a motion, is expressive, while waiting (for Godot etc.) is futile/leisure - with or without a possible meaning/effect of this leisure for the ones who are waiting—or (which can be part of a work again): to pause and to take time etc.

In the above case, I would use poststructuralism as basic perspective. With a view on the (assumed picture of the) structural shaping of life and the flowing of these structures.

The approach "towards"* a theory of work would yet be an existential one, because it would be a theory of Praxis?

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* Richard Dawkins has mocked the "towards" in the title and content of social science articles lately.

Poststructuralism would certainly work better in such a way which is suggested in your question. However, some points are very important in order to understand such an answer. Labels in general (such as Poststructuralism, critical theory, existentialism) explain little on relevant issues on theorical debate. It is necessary to answer some important questions: which especific epistemological references  are taken into account in each of these perspectives? Do these references or authors allow to have a coerent and understandable theoretical approach in terms of "translating" them to concrete empirical investigations strategies? The meaning of "better" is very relevant. It certainly has different menanings to be condidered in terms of an appropriated answer.

@Rodrigo Passos:   Yes, I would try to work (?!) on (poststructuralist: temporary and partial/aspectual?) definitions of the meaning of the used terms (like 'better'). And I would try to make the epistemological and ontological groundworks operationalisable.

References from literature, theoretical groundwork and perspectives/chains of reasoning, or (about) empirical aspects would be good.

The key-word is "ressignification". It may be a failure on my own research, but I can not recognize a possible answer if difficulty with ecletism concerning structuralism, existentialism, critical theory etc concepts is not solved. In the same manner, I do not know references which are published on these dealing specifically with IR theory. But I will  send you publications of my own when they are available. I will attach some texts about ti in Portuguese. You can understand them with translators such as the ones of Google. They have been written by a Professor whose classes i attended to many years ago. His reflection inspires me to write this answer to you

In other words, you can only use concepts in terms of investigation strategies if they are properly ressignified in order not to be incompatible with each other. That is the main difficulty of using categories, concepts of different authors and theories. They can only work properly with each other if they are ressignified in compatible terms with each other. On the contrary, they are not workable in terms of investigation strategies. 

I am attaching some published texts in Portuguese which deal little with limits of ecleticism. These texts are mine. One concerns Gramsci and critical theory of IR according to Robert W. Cox: "Gramsci e a teoria crítica das Relações Internacionais". The other was published in a book and its title is: "A Segurança Internacional no Pós-Guerra Fria sob o ponto de vista da Teoria Crítica" and deals with critical theory literature concerning international security. Both articles analyse limits of ecleticism in critical theory. The second one begins an alternative proposition in terms of getting thorugh with ecleticism.

In semiotic terms, silence is not the same as absence of meaning, but its counterpoint. Work and leisure seem to function in analogous ways. It is important to consider your question from two separate perspectives, the private and the public ones:

1. Work and leisure as they alternate in counterpoint-pendular movement in one person's life.

2. Work and leisure as pendular moments alternating in the overall economic system.

The fusion of both needs and economic provision for it could 

On the other hand, the question of will and desire (Kristeva) cannot be obviated...

Being out of work for redundancy reasons and leisure are not the same, cf. Thorstein Veblen