I'd say that the question sort of answers itself.... the aesthetics generally drive my choice. If the installation ends up looking nice, and isn't functionally hampered by the location, then I'd say that it is fine.
Personally, I like to keep the clutter away from the handlebars, so I've got a braze-on on the fork of my commuting bike for mounting a light. Previously, I'd used a fork clamp mount, but this tended to collect dirt and had a risk of damaging the paint.
Steve in Peoria