Not sure one is better theoretically, but super GM's play the Ruy Lopez most frequently when it's an important match on the line! At our level, it doesn't matter.
I started playing chess with the Ruy Lopez, then years later switched to Italian, which I still play. I like Italian better...
1) It has a lot of different strong variations to try out. Risky? Try Evans Gambit. Positional? Giuoco Pianissimo. And everything in between. I find the Ruy Lopez follows the same moves more often.
2) Italian targets the weak f7 square right away. I find this more fun then attacking the knight. It makes for some cool tactical chances.
All I got for now... Might add more when they come to mind Lol
Which is better theoretically ? The Ruy Lopez or The Italian Game? Also which one do you prefer and why ?