Any discussion about patterns of Embrace in the Sabbat needs to be prefaced with a disclaimer or two. First of all, Sabbat habits will vary radically from game to game: you or your ST may not agree with how I see things among the Sabbat clans. Second, these principles naturally only apply to those Sabbat who are actually chosen by their sires for some positive reason. 'Shovelheads' may eventually work their way up in the ranks of the sect, but as they are chosen more for convenience than anything else, there are fewer patterns to analyze.
Historically, the Lasombra were dark rulers, the shadowy forces behind the throne. They saw themselves as manipulators, possessing the skill necessary to control the rulers instead of standing forth as rulers themselves. While men were certainly more likely to have the influence and power that the Lasombra appreciate and crave, especially among mortal courts, a significant number of women possessed the traits the Lasombra respected as well. Female courtiers had no recourse to the armies and wealth their male compatriots used as pawns. Instead, they were forced to develop skills of manipulation and subtle control, encouraging their more palatable consorts to do their will. The Lasombra would never have overlooked such abilities, especially in those already of noble blood. Though elder, female Lasombra likely number slightly fewer than half the ancients of the clan, they are a highly significant - and dangerous - minority.
In modern times, as the Sabbat has grown in power, the Lasombra have become more interested in direct leadership, whether at the level of pack control or struggles for control of the entire sect. Aggression has come to be valued over subtlety among many of the younger ones, though the reasons for this are debatable: a lack of vision, the temptations of having achieved power, the need for a final push against the enemies of the sect? In any case, even today, men are socialized to be significantly more aggressive than women. In modern nights, therefore, the Lasombra are more heavily male than in olden times.
The ancient Tzimisce were open lords of Eastern Europe. They saw themselves as the masters of the land, ruling their people with force of law and terror. The feudal mindset made it rather more likely that men would be in positions of temporal power and dominion, with some notable exceptions such as Tzimisce par excellence Elizabeth Bathory. Thanks to the Tzimisce attitude that mortals were to be culled and selected, with only the best chosen for the Embrace, many of their childer came from this group; after all, what better contest for survival than the struggle for mundane power? On the other hand, the Tzimisce have complete control of the flesh, and did not need to be bound by the original gender of their choices. Certainly there is little way of telling which of these ancient monsters were originally possessed of what anatomical details - and gender itself means little more than a detail to this strange clan.
In modern nights, the Tzimisce are equally inhuman, but they focus more on scholarship than on rulership. While they still feel that only the most extraordinary mortals are worth being more than subjects for their twisted experiments, their definition of extraordinary has changed. Scientific brilliance might be one criterion, while a particularly inventive torturous mind might appeal to another Tzimisce. Rationality and inquisitiveness are the main unifying factors among the chosen of this clan. Until quite recently, women were deemed inherently irrational (thanks to spurious biological 'research'), making them less likely to be chosen by the clan. However, the Tzimisce are nothing if not willing to see the spark of genius in unconventional places, and many of them might even enjoy helping women discover their unexplored ... capacities. Until recently, women have been much more concerned with appearance and fleshly manipulation than men, something that would certainly appeal to the twisted understanding of the clan. Additionally, the Tzimisce fascination with the creation and shaping of life might spur them to choose children who were already experienced with such things: mothers. For this reason, even though the modern Tzimisce have had less time to forget their original shapes, the clan is only slightly more than 50% male.
The Antitribu come from two main sources - fresh blood that joins the Sabbat from the other clans, and the childer of existing Sabbat members. The sources do, however, maintain their original clan outlooks at least to some extent. Though this may vary by clan, I will only address the clans in which there are likely to be significant philosophical or practical differences from the root clan, and do so only briefly.
Assamite: These Antitribu are almost entirely made up of assassins, and as such they maintain the gender characteristics of that portion of the parent clan. However, since their training schemes are shorter and more violent (as everything in the Sabbat tends to be), they likely choose more of those who come to them with the necessary skills of assassination and war - and so are more male than the equivalent portion of the parent clan.
Brujah: Rebels and children of rebels alike, they value martial prowess, violence, and aggression. Without the tempering idealism of the parent clan, they are more heavily male as well.
Gangrel: The strongly independent nature of the Gangrel means these beasts are little different from the parent clan.
Malkavian: Incurably insane and without rhyme or reason - even more so than their parent clan. Statistically, though, this means they are likely equally divided between men and women.
Nosferatu: Are the Sabbat members among them even truly Antitribu? Probably much like the parent clan (despite White Wolf's comment that Nosferatu Antitribu are mostly male).
Ravnos: Less philosophical, more criminal; less concerned with Rom ties and more concerned with charisma and wit. The two balance each other out, leaving these wanderers with a relatively equal balance of men and women in their ranks.
Setite: They value intelligence and mysticism more than sheer corruptive power. Though they are less under the sway of Judeo-Christian beliefs about women, priestesses as well as priests make up their number, leaving them quite evenly gender-balanced.
Toreador: Though they claim a truer understanding of aesthetics than their Camarilla siblings, they are little different in terms of their underlying values and choices of childer.
Ventrue: Unlike their Camarilla counterparts, the Sabbat Ventrue are less interested in wealth, power and position and more in the responsibility that comes with such things. These dark knights are therefore far more likely to embrace women, simply because there are fewer factors impeding that choice.