Cows are generally not a good idea for small land holdings, they are large animals and as such require a lot of space, you can purchase them as caves or weaners, the calves require alot of care and feeding until they are weaned of the milk they require
Sheep are fairly easy animals to keep on a self sufficient farm they take less space to feed than cows, they require regular shearing in the summer months and there fleece can be sold at market they can also be breed for sale or as meat for food.
Pigs have got to be the most fascinating of animals to raise on a farm every pig has there own personality and they also make great pets when needed, they can take up a small space in a pen or they can roam the paddocks, pigs are also good recyclers of food scraps.
Goats are good a choice for self sufficient farms they are very active and love to jump and play on objects in the paddock, they are good for the table and there fleece can fetch good prices at market, the only downside with goats is you cannot let them get to your vegetable patch or any trees they will demolish them.
Deer are an option if you have a large property to keep them on, they are expensive to set up as the fencing is required to be high to prevent them escaping back into the wild, they are a specialist animal and require alot of work but they can be worth a great deal of money on resale..