New Book Ending

I'm working on this one book that I originally wrote way back in high school. The characters were bugging me a few months ago, so I took out the book. It was horrible. Really bad. But, the storyline was good, the characters were good. It just needed a lot of tweaking.

Basically, I grabbed the character's names and personalities and wrote a whole new story, keeping some of the same story. But, now I'm getting to a part where I could go a few different ways with it.

I could keep the original type of ending - happy, predictable.

I could make the ending sad and not so predictable.

I could make the ending not what I wanted, but probably more realistic. Happy, yet not happy.

I read so many people get tired of predictable, happy endings. But, how many readers are like that? Most? Some? Only a few?

And I LIKE the happy endings. So, should I just write what I would want to happen even if it's predictable and happy?

I'm sure I'll write whatever comes to me at the second I get to that crossroads. But, right now, I'm kind of conflicted about what to do.