I have two children and love them both dearly and equally if not exactly the same. My oldest child and I have always been very close as she was a particularly needy baby and toddler (she outgrew it). My youngest child is a delight, easy-going and so pleasing to be around. When my oldest child married, the youngest still lived at home and we had so much fun in that 5 years before she married. We also are very close.
My youngest child frustrated me more than the first. She was more mischievous and got into things a a small child. She outgrew this to become a wonderful caring adult.
But I love them both so much and could never choose between them.