Neither.
Both vehicles only come with 4 cylinder engines. A V6 would be nice, a V8 would be better yet. Both cars have the styling to pull it off.
The Hyundai Genesis Coupe will offer the choice of a 4 cylin turbo, a V6 or a 350 H.P. V8. Hyundai doesn't offer it in a top down model....yet. Look for it in Spring '09.