There is not much different in male and female yorkshire terriers !!
The only different is that the bitch goes in heat 2 a year for about 3-4 weeks at a time (that is propably why someone said to you to get boy not girl, many people can't stand having bitches in heat but its not really a big deal you just have to watch out she isnt around males at that time unless they are neutered, if you spay her this heat deal will go away!).
Male yorkies often have more energy and are much more hyper, but bitches are often very calm (but not all, I know very calm male and a hyper bitch !).
Dont change your mind becouse of something some person said, I love both male and female dogs
