Fixing the issue first, a roof, furnace or foundation problem, usually supports a stronger price because it removes the uncertainty a buyer's own home inspection, typically $400 to $600, would otherwise raise as a negotiating point during the condition period.
Selling as-is is a legitimate path when the repair cost or timeline does not make sense for you, but expect buyers to price the risk into their offer, often more conservatively than the actual repair cost, because they cannot be certain what else the issue has affected.
The right call depends on the specific repair, your timeline and what comparable sold homes with similar issues have actually fetched. Get your hand-reviewed valuation from Joel Dyck.