I'd say match the toe kick. (Architects do have better design eyes than contractors. :))

Having the top rail at 5.5" it might make it look top heavy, so maybe the Architects idea of matching the tock kick would look best. Here is some ideas that we had pulled together for the island outlets that might be of some interest ...

Kitchen Island Outlet Ideas

I have mine buitin to the end of my island similar ti the Jill Jordan one above without the cover but don’t see why you couldn’t do something like that without the top rail.

We have also put receptacles and switches in the island behind a false drawer front. Here is another that is mounted in the bookcase cabinet on the interior (working) side of the island. The electrical box, which is inside the bookcase is covered by a box made of stained cherry wood matching the island. You cannot tell the box is in the bookcase. The frame on the bookcase is arched in proportion to the unit - not aligned with drawer fronts or toe kick.

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