Any of them, as long as it has the Rotax parallel 798cc twin. My Dad has a bike with this engine in it now and it sounds weird. Almost like a really subtle Subie/Boxer rumble to it. Kind of like a quad, almost.* So do they all sound like this? It's an 08 F650GS Twin if it helps.
*This engine is in the Can Am Outlander quad as well so that's a bad analogy.