I LOVE Go Fish. I mean, yea, it's definitely not the best episode in the world, but it was the first episode I ever saw, so it will always hold a special place in my heart.
It's hard to decide between the other two... On one hand, I don't consider Reptile Boy to be bad.. just mildly boring. On the other hand, Inca Mummy Girl is definitely a worse episode, but Empada's (sp?) story is legitimately moving and it was nice to see Xander fall in love (as well as push Willow to look elsewhere).
I choose Reptile Boy! Due to not really having an emotional connection with it.
I wouldn't say that it was legitimately moving for me. It was nice that they made that link to Buffy, and it made Empada a less black and white monster of the week. But there wasn't enough thought put into it to really make me care. I was never convinced that Empada should be forgiven for her actions.