Preferably the kind with a hose leading from the tank on your belt to a hand-held flammenwerfer. They're easier to use in tight spaces. You can just burn all those cobwebs and spiders back as you advance. It's like magic and very satisfying.
In a past life I spent most of my days under every kind of house and spider infestation imaginable and never had any issues due to the flammenwerfer.
Below the photo you will find a link to one example of many hose extensions. You don't get a giant flame. It's just the normal flame you'd get with the gay nozzle that screws directly onto the bottle. It's very safe and controllable. You do want a self-igniting torch head for this application so you can light it without any fuss to burn a web or denizen thereof. I prefer the trigger type.