Israel should annex Gaza.
Israel shouldn't annex the West Bank.
After Israel annexes Gaza, Israel should wipe out any and all members of Hamas that they can get their hands on, and immediately instate full and equal rights to the people living in Gaza.
That should include voting rights for everybody eighteen and older.
As many people have pointed out, the population of Gaza is predominantly young people.
Their right to vote won't overthrow the democracy of Israel. Once people realize that they're better off and living better lives as citizens of Israel, many of them will vote accordingly.
You're never gonna get rid of Jihadists entirely. You can show them that a better life is available.
Gaza would be Israeli land today if it weren't for Israel being naïve, and thinking that giving the land back to the Muslims would be a step toward peace.
Israel should just take it back, destroy Hamas, expand the borders, and show to the world that is better to live in a western democracy than it is to live in a theocratic dictatorship.