The Spanish is played way more often at the world-class level. Below master level quite possibly the IG is "better" because it's way less complex and has way fewer variations. Anyone below Master level should at least be familar with some double KP Openings except the RL before playing the RL in serious games.
The DB here is hardly the alpha and the omega on this subject but it does help indicate how much more popular the RL is over the IG (by a ratio of 5:1 in this DB)
Whatever you know best.
The Spanish has more theory and richer possibilities. It does require good positional understanding to play both colors, and it is probably the best chess strategy course one can attend.
The "modern" Italian (with d2-d3) is a relatively quiet opening, but it would be a mistake to reject it as harmless.
My own suggestion for new players is to start with a more straightforward opening, like the Scotch.
Both allow 1...e5 so neither. Play 1.d4!
But doesn't that allow 1...d5?
Then 2.c4!. Center game or King’s gambit are gross.
Italian: Less theory, avoids Berlin, Marshall attack, and all of that Archangel stuff. It was Kramnik’s choice when he played 1.e4.
The title says it all... Which is better? Spanish or italian opening?