personally i dont even see Western RPGs and Japanese RPGs them in the same catagory. yes they are RPG's but they're similar in the way a bannana and a coconut are both fruit, and both are wraped delectibly in natural less than digestible organic armor completley covering thier fleshy centers. but when it gets right down to flavor, aroma, and asthetics the shear number of differences are staggering.
and what quallifies as a "Western" RPG anyway. would say diablo count as a western RPG, or Fallout 3, World of Warcraft. three games so increadibly different in play style, story and and artistic choice that conmpairing them goes back to the cliche fuite debate.
lets looks at JRPG's for a moment
i like some JRPG's for there dependible, and generally easy to use mechanics. i love that the games value story. however i am tired of the american facination with japan, i understand that japanese stories are new and exciting but there only new and exciting because the culture has developed diferently than ours and therefore has different cliches, and you see them in all JRPG's. the main character is male usually under age (<21, often <18) will have some trial to pass while he collects friends and items all of which are mor intersting than the bland lump of clay your main character is. the first male side character will be comic relief that will forgo humor in a moments notice the fall in love with one of the female side character an act usually over looked by said character as the comic relief has often hit on other women. ther will be a prime number of side character usually 3, 5, or 7. then there will be a big boss battle and at least one of the main will die at the hands of the boss at some point in the journey and there is always a journey. then theres a turn based combat system.
its all so particular to JRPG's its hard to say "western" RPG's are better or worse just because they are so different.