I'm juggling three teen fantasy/sci fi series right now because I was a little burnt out on the heavier stuff and I just wanted a good story, dangit!
The three are:
the Lorien Legacies,
Ashfall (holy crap, this may be the first topic I couldn't find a wiki on, like ever), and
the Mortal Instruments.
They all got good concepts.
The Lorien Legacies follows a group of alien teenagers stranded on Earth that need to develop their powers to defeat the evil aliens that destroyed their home planet. Ashfall follows a teen and his girlfriend as they navigate through post-apocalyptic America after the Yellowstone volcano blows. The Mortal Instruments are about a race of humans that protect the rest of us from demons and other fey.
Like I said: Cool concepts.
But they all have the same problem: No matter how serious a jam they are in, or how cool what they are doing is, it all boils down to how much the guy likes her, or what the girl thinks about him, or omg aliens are trying to kill us but all that matters is I go see the girl I've been dating for like 2 whole weeks!
It makes them nearly impossible to enjoy. The Mortal Instruments is the worst. It's basically Twilight: Girl meets impossibly perfect guy, is pretty pathetic at basically everything, and then their love becomes forbidden causing extreme mental anguish. Blrch. Just go kill some demons already! Or, spend some time training to be an absolute ****** rather than mooning over some boy and moaning about how you will never be as perfect as him.
Ashfall is probably the least worst in this department (though the protagonist does fall into an impossibly strong love-relationship at the ripe age of 15).
The other problem is that most of their problems stem from
just not telling anyone about it. Half the books would be solved from the get-go if they just went up to the appropriate adult and said "Yo. This is what's going on."
Le sigh. I suppose that's what you get when you read stuff meant for teens. Teens probably eat up that independent crap, even when it leads to demonstrably worse scenarios.