Welcome to YT! I don't know that much about Chihuahua's but I always thought they were yappy, crazy little dogs. Every one i met barked a lot, there are even 2 right now in my building that bark like crazy when anyone passed by the apt. But then again im sure other ppl think of Yorkies in the same way, as little yappy dogs. The truth is though there are some chihuahuas that are yappy, not all of them are. They all have different personalities as do Yorkies. My vote of course goes to the Yorkie
I think they are both cute though, maybe in the future i will get a chi. Personally i like that Yorkies have long hair so i can put bows in it, and do diff. things to it. I also like brushing it and maintaining it but not every one does. You don't have to do that to chi's unless they are long haired. I think Yorkies have the best personalities tho
Good luck!