Very generally speaking, the older the game, the less skill is involved. Skillfully juggling and shooting 3 or 4 balls at a time on AC/DC is a lot harder than knocking down drop targets on El Dorado one ball at a time. Old game, more luck (house balls). New game, more skill.

Classic tournaments typically get more entries than 'modern' tournaments. They don't get as many cameras or spectators, but more folks feel like they have a chance in a classic division. Often the same guys winning modern will win classics. Which kinda proves that practice is way more important than game choice.