Can you share which state you're in, your state tax rate, and amount you plan to contribute? It's a math problem of whether the drag from bad investment options/high fees outweighs the tax savings from contributing to the eligible state plan. In most cases, the tax benefits still win.

You should also be aware, you can't just open a "fidelity" 529. Fidelity manages a few state plans (Arizona, Mass, Connecticut, Delaware, and New Hampshire), and for non-residents who still want a fidelity-managed plan, they route them to the NH.

Though even in that plan, you don't get access to the full suite of Fidelity funds. They have a few options for managed portfolios that you can choose.

Same goes for Vanguard plans. They manage New York, Colorado, and Nevada's plans, and route non-residents to their Nevada plan.