Brief evaluations of some of the English versions of the Chuang Tzu:

David Hinton, Chuang Tzu: The Inner Chapters
This version strikes me as less clear and crisp than Watson, but less lively than Hamill and Seaton. One might want a version of just the inner chapters, especially for teaching something short and sweet. And this version sits nicely in the hand and is not terrible. But it isn't great either.

Burton Watson, Chuang Tzu: Basic Writings and The Complete Works of Chuang Tzu (Columbia University Press, 1964 and 1968).
I've taught the shorter Watson many times with great success. It is clear good English but also not without a certain flair. To be totally honest, I'm not convinced that any later translations are real improvements or are really necessary. I do wish there was an inexpensive paperback of the longer text, even though I mostly agree with the excisions that lead to Basic Writings.

Thomas Merton, The Way of Chuang Tzu (New Directions, 1965)
What you'd expect from Merton: beautiful English and a deep understanding of both the contemplative and absurdist moments of the text. It's not systematic; it presents bits of the text almost as a series of poems. But is also gives you the essence of Chuang Tzu right off the bat, beautifully.

Fung Yu-Lan, Chuang Tzu: A New Selected Translation with an Exposition of the Philosophy of Kuo Hsiang (Foreign Language Press, 1931)
Only the "inner" chapters (1-7 out of 33). These are considered most likely to be authentic or attributable to Chuang Chou himself, for reasons that remain a touch obscure to me, especially as I feel the essence of the book is contained in chapter 17. Also Fung writes a strained or perhaps incompetent English prose. Nevertheless, this edition has the incomparable advantage of presenting the text with Kuo Hsiang's great commentaries: one of the greatest works of Chinese, or indeed world philosophy.

Sam Hamill and J. P. Seaton, The Essential Chuang Tzu (Shambhala, 1999)
I am teaching this at the moment, because the Watson was unavailable this semester. I'm glad I did, because this thing has great flair (Hamill is a poet). I have quibbles (like Mair, they use the phrase "all under heaven." "Hide the world in the world" (Watson) is amazing; "hide all under heaven in all under heaven" is just boring). Also there are things I would have omitted (chapter 8) and things I wish they had included (33). But they give a fresh spirit to many passages and even the text as a whole, which comes out very surreal and brand new.

Victor Mair, Wandering on the Way (Bantam, 1994)
The complete text, and a prodigious labor. Also, there is probably much to be said for it philologically. Nevertheless it seems to me flat and laborious in English. It's missing some kind of spark, or delight, or rhythm, or something. I'm against it.