I really dislike it when I read a Mystery, and at the end the motive seems to be extremely fake, or over the top.

How do you chose a good motive that fits in with your MC's character? How do you create a unique motive without it being far fetched, or over the top?

I haven't attempted to write mystery yet, but I do agree that the motive matters a great deal. I've come across mystery novels that, when I read the end and learned the reason, it was just so..."meh."

I think it has to be believable and nothing too far-fetched and absurd. Or something so cliche as to be boring.

I know, I like to be surprised, and definitely not disappointed at the end of a mystery.