I don't think that nonviolent felons should be banned from voting. They're still people, and they're still citizens, and they should have the right to have a voice in the way their nation is governed. If they served their time, they should be able to vote. Just because someone bought some drugs, or made some mistakes in their youth doesn't mean they should be wholesale disenfranchised.
Voting should be a right, not a privilege the government can arbitrarily take away. Voting is the lifeblood of a democracy.