People always used to say that crocodiles were the best thing to farm in vanilla because of their huge egg numbers, as well as turkeys for how quickly they grow. Are they still some of the best candidates in Masterwork?
What about out of the orc domestic animals? Squigs obviously breed super quick, but I presume don't give much when butchered. Also their multi-caste thing makes autobutcher a bit more awkward.
How about the optional randomised procedurally generated creatures that Masterwork adds? Are their brood-size, maturation times, etc randomised as well? Are any of them particularly good for farming?
How about the Deeper Dwarven Domestication mod? The cave turtles seem to have pretty large clutch sizes, but think they take a while to grow.
Getting leather and bones is more important to me than meat or eggs, seeing as how easy food is to come by in DF. Also worth considering whether something gives leather, shell, scale or horn, given e.g. you can't use scale to make lamellar.