For a young kid starting off in the hobby who knows absolutely nothing, I wouldn't recommend any monsterfish. I'd encourage them to learn the ropes with "mini monsters". Don't try to run before you can walk in this hobby.
A few years getting some valuable base experience will set you up well for when you take that next step into the realm of keeping big fish.
Another point worth noting is that keeping monsterfish can be expensive. How many young beginners have a means to fund such expense, or even own their own property so they can decide what sized tank they can have?