Well, this is perfect, as I'm 14 myself

Of course, I enjoy science fiction...but many of my favorites aren't of that genre. Sorry for not knowing all of the authors' names. If you're interested in one, let me know and I'll look it up on my bookshelf. (I'm at dad's right now)
The Outsiders, by Hinton: A slim volume, but one of the best books I've EVER read. Ponyboy and his brothers live together deep in a crummy city, (orphans,) where you have to watch your back every second to keep from being killed. Major adventure; wild ending.
The Only Alien on the Planet: Honest, it's not science fiction!

The main character never smiles, never speaks, shows absolutely no emotion to a soul; until Ginny, the new girl, comes along. (By the way, he does great in school and is literally a genius). Wait untill you find out why he's locked up inside himself....
The Giver by Lois Lowry: Ok, so this IS science fiction, but it's so unbelievable I would never forgive myself for not reccomending it!
In the Stone Circle by Elizabeth Cody Kimmel: Ok, so there are mysterious spirits and stuff in this one...but it's definitely one of my favorites

If I think of any more I'll let you know.