Basically this.
Loved them, can't stand them anymore.
Edit: Obviously there are exceptions (hello, Dark Souls), but I get nauseous about the whole "THIS GUY IS MORE POWERFUL THAN A GOD AND CAN DESTROY THE WHOLE UNIVERSE AND ONLY THIS 12 YEAR OLD BOY (yes, he does look like a girl but it's a boy) CAN DEFEAT HIM USING WEIRD-SHAPED, UNPRACTICAL WEAPONS". Maybe because I'm not 12 anymore.
While I find child (or anybody really) protagonists wielding swords the size of a car and fighting gods to be a bit silly too, I'm just as jaded with the typical western equivalent. "There is a complex political and military situation involving thousands of people from multiple factions, and only muscleguy can solve it by personally killing thousands of people, shrugging off thousands of mortal bullet/axe wounds by crouching for five seconds, and then shooting/stabbing the corrupt general zod in the face in single combat. This will resolve all the gameworld's problems instantly, as the evil general's plans are all bizarrely linked to his lifesigns."
Both are just wish fulfillment and terrible writing bolted onto a game mechanic, usually decent, fun combat. I mean, take Shepherd, for example. Commander of a spaceship, secret agent, instigator of the greatest alliance the galaxy has ever known, and he still gets used as a skirmisher in whatever battle needs fighting, not to mention saving the universe by eliminating various all-powerful aliens personally and usually within spitting distance rather than from the deck of his incredibly powerful spaceship several hundred thousand kilometres away. The relative difference in personal physical power between him and a small child when fighting these 'gods' is irrelevant. Both are so far out of their league that they shouldn't be able to do it, but both do much to state that it's the player character's sheer tenacity and willpower that matters more than their strength. It's just that a thirty-year-old western player feels more comfortable with a thirty-year-old space marine changing the fate of the world/galaxy/universe rather than someone 14 years younger, as if that makes much of a difference when facing down something thats billions of years old and offers a million-to-one chance of success. Both variants are ego-stroking, focused on the player character being the only possible agent of change in the whole game world. Fortunately both cliches aren't the only Western or Japanese games available.
I think my main issue with teenage characters isn't beating up gods or toting weapons the size of lamp posts, when adults shouldnt really be able to do it either. It's more mundane stuff, like being ace detectives or military commanders when adults with thirty years of job experience are shown as being idiots in comparison. When a child character just physically can't have had the life experience required to master all of the practical, social and academic sides of the skillset, but they display a ridiculously extreme level of worldliness.
To answer the OP, I play a split of about 70/30 in favour of Japanese games, but not just for the rpgs. A lot of that is the older action stuff like Castlevania, Megaman and Contra. I have a noticable preference for games with tight mechanics and without hours of cut scenes no matter who makes them. Plus I was introduced to those series on the NES, and still play a lot of Nintendo games. Most of the western games I play are newer indie games.
