Headlight has much better graphics, it is an up to date game. You have the opportunity to buy service stations, hotels and more. You will not get boring so fast, it is a game with many possibilities.
For me headlight is the most promising game :)

PD: I also like Rign Roll i hope it will be launched soon..

Good graphics and opportunity to buy/do something doesn't make the game good if physics, sounds sucks so we have to wait and try out both games and decide which is better :)