Western; I love having a hand in how my character looks, and upgrading equipment and having my character reflect that.
In Jrpg's, no matter how much you've upgraded by end-game, you'll be wearing the same fruity little outfit you started in.
Also the difference in storytelling. In FF and most other Japanese developed games like Metal Gear, the story is told in long-winded cutscenes that you just sit back and watch. Western games (mostly rpg's in this case) do so through dialogue/conversation, and for the most part, you actually have choices to make that impact things in some way.
Basically, I look for fun,
replayable games to take up space on my hard drive, and Jrpg's are a bit lacking in the replay-ability department, what with linear (and often times convoluted) stories, and the utter lack of visual customization. On the flipside, in BioWare and Bethesda developed games, you can play through a variety of ways, either by way of your class and/or playing things good or evil in conversations... while Western stories may be a bit cliche' or dull at times, they're markedly easier to follow. :/