I know which of the two I’d rather have. And it’s a bad first draft.
A bad first draft shows that you’re writing. It shows that you’re not intimidated by the empty page or by the task at hand.
A bad first draft is a start. It’s a base on which you can build a finished product. It shows that you’re serious about your ideas and want to try to see them through.
A blank page is, literally, nothing. It shows you’ve fallen victim to perfectionism paralysis.
A blank page shows you don’t appreciate your ideas enough to get started, let alone to finish them. It shows that you’re not serious about writing.
A first draft, regardless of its quality, isn’t perfect. It’s not supposed to be perfect. Don’t expect it to be. But you can shape a bad first draft into something better. You can edit and rewrite a bad first draft to improve it. You can’t do that with a blank page.
Write that first draft. Don’t worry about how good or bad it is. Embrace that first draft and finish what you’re writing.
If you do that, you’ll improve. You’ll be ahead of writers who let the demon that's perfectionism stand in their way.