The Arabian Nights: Tales of 1,001 Nights: Volume 1 (Penguin Classics)
There is probably no 'one' master text for the Arabian nights but if you're hoping to read the complete stories, the three volume Penguin version is as good as you're going to get.
The translation, by Malcolm Lyons, is modern and close to the Arabic: for example, "your wish is my command" is rendered as "to hear is to obey". Other reviewers have complained that it's pedestrian, but I found it very easy to read, and full of life.
Oddly, certain really famous stories whose origins are in the Arabian Nights are not in the 'master' text in Arabic; for example, Ali Baba and the Forty Thieves only exists in a French translation made by Antoine Galland, but is added to the end of this volume. By contrast Sindbad is within the original text, but his story cycle is found in Volume 2 of these stories, if you're looking for that.
Anyway, what is it all about?
What you find are hundreds of overlapping stories, with certain overarching story cycles, that are artificially laid out over 1001 nights. Handsome men are bewitched by women with jutting breasts and faces like the moon, before discovering that in fact they are the long lost cousin of a caliph or whatever; and it's a very dangerous world out there: the number of corpses puts 'Game of Thrones' to shame, because it doesn't take much for your head to be cut off by an angry shaikh.
My favourite story cycles in this volume in were the story of King 'Umar ibn al-Nu'man and his family, and the story of King Shahriman and his sons, neither of which I'd heard before.
The first is set in an uber-conflict between Christian forces, whose heroine is a witch type character Dhat al-Dawahi, endlessly tricking the Muslim heroes to their doom, and Muslim forces, who end up laying siege to the Christian capital in the east, but don't fully win the day. The second is a tale of sexual confusion where men fall in love with women thinking they are men; stepmothers fall in love with stepsons; and there are all manner of twists and tales (and comparisons to be made with Phaedra and Hippolytus and Joseph and Potiphar's wife, from other ancient sources).
This volume probably isn't to be read in one 'go' but equally it's worth doing more than just one or two 'nights' here and there, but sticking it through individual cycles, as otherwise you'll lose track of the characters: which brother has been left for dead on a scrapheap in Baghdad; which sister has been married to a caliph in Damascus, and so on. Luckily, this edition tells you when the cycles end, in a handy index.
Other people have commented on the morals of the stories, but that's much less a theme, I'd argue, than the danger of being tempted by a beautiful woman, whose eyes bewitch you into doing something you later regret; more generously, the stories are full of the overwhelming power of passion, which means people do foolish things.
The characters on one level are mostly Muslims and the Quran is quoted quite often, but that doesn't mean the characters don't drink copious amounts of wine, or lust after and sleep with countless princesses and courtesans. It's incredibly unpredictable: people move from rags to riches and back to rags again, and the hero definitely doesn't always get the girl; sometimes, they just die from pining for their love, who is stranded in a kingdom far away. Some of the time, the humans have been confused by wandering djinns, but on most occasions, they contrive problems of their own.
The whole is enjoyable in a weird and wonderful way, and depicts a far-off world in a far-off time. It's escapism, and a story-teller's delight.