Whatever works best, depending on the game. Really, this is a bad question as each game plays differently. Textropolis would be pointless with tilt controls and Tiltafun would be useless with touch controls.
I like a hyrbid, but for racing, it's definately tilt. For most other games, I like touch. Like in Star Wars, I loved making different patterns on the screen to use the force. Reminded me of using magic in Black & White. But why not integrate them both if the hardware is there?
