Chris,
If you're after increased flavor, then IMO, I'd opt for the marinade. Brisket is a big, heavy piece of beef, so let it marinate for a good 24 hours. Here's a quick recipe and you can adjust/substitute as you wish:
* 1 1/2 cups red wine
* 1/2 cup olive oil
* 1 1/2 tablespoons mustard
* 1 1/2 tablespoons lemon juice
* 1 tablespoon wine vinegar
* 1 tablespoon horseradish
* 1 1/2 teaspoons salt
* 1 teaspoon cayenne pepper
* 1 teaspoon onion powder
* 1 teaspoon garlic powder
Paul