Most of my cockatiels loved spinach, dandelion greens, broccoli, and kale. It is very important that if one is breeding cockatiels to make sure their birds have a lot of vitamins. Always have a cuttle bone, and make sure one feeds a variety. Lovebirds have a bad rap for being nasty. I feel if one has only one lovebird and holds it at least everyday than it will be a faithful pet.
Females tend to be nippier than males.
My Grandma has a baby lovebird that I raised. The lovebird has to be every where she has to be. If one is not going to be home a lot, or wants birds, but doesn t want the bother of holding them, then I would suggest a pair of lovebirds. Make sure that the pair is not related. Mainly in case they want a family.