So, would you recommend me to buy an Asus GTX760 or the MSI GTX770 Lightning LE? The price difference being about 60e in favor of 760?
Depends on your monitor. If you have less than a 1080p monitor a 760 should run most current games on high right now. if you have a 1080p monitor go with the 770. If the 60e doesn't matter much go with the 770 as it is a much faster card.