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It's weird you don't pick an app because it looks different, even though the competition sucks... I prefer KDE apps, but I use amule anyway. In KDE, of course, we have the luxury of the GTK-QT theme, so the Gnome apps look like KDE apps, but you could also choose a KDE theme which looks similair to your gnome theme. Besides, most Gnome desktops have a mix of Gnome and plain-gtk apps, some don't follow the guidelines anyway, so you won't have a perfect consistent desktop anyway...
Still KDE and Gnome are both ahead in consistency on Win and Mac ;-)