Under the new Afforable Care Act, you cannot be declined for an individual health insurance plan due to a pre-existing condition or other health-related issue.
You have the option to secure a bronze, silver, gold, or platinum level plan. Keep in mind, however, not every carrier offers a plan under each level (e.g. company XYZ may only offer bronze, silver, and gold plans, but not platinum plans). Individuals under age 30 also have the option of securing a catastrophic plan.
If you qualify for a subsidy, you would want to look into plans ON the health insurance exchanges. If you don’t qualify for one, you may want to look into plans OFF the exchanges as you will generally have more options available to you.