Columnar box or Japanese holly. However, if you do not have a geometrically symmetric house with corresponding formal bed layout I would avoid matching pairs.

I thought of Japanese Holly, but was hoping for something more interesting.

For the most part the interest in formal layouts - where the plants are often sheared, thereby further reducing their individuality - is in the pattern made by the plants and gravel etc., not the plants themselves. If you are planting an identical pair at the gate you are emphasizing the shape of the gate, with the shrubs just being a couple of exclamation marks beside it and not separate features planted for their own sakes.

And again, if - as is usually the case - the surrounding planting and architecture is not formally symmetric then the gate combo doesn't fit in, being instead like a tuxedo at a picnic. If you do not have a geometrically defined setting you should instead design something at the gate that will produce informal balance, for instance a smaller and an intermediately sized shrub on the left and a larger shrub on the right - each a different kind - so that the volume of growth on both sides is ~equivalent but the plants are not twins.

My garden was inspired somewhat by Gertrude Jeykll. Her formally shaped, but informally planted, beds seemed appropriate for my 1916 house. The beds have mixed plantings with an emphasis on layers rather than perennials. I am trained in garden design, but it's a constant struggle between design and plant lust. Which is why I was hoping for something more interesting than Japanese Holly.

It's true I don't need matching plants. I really only have matching Cornus there now, because I broke a twig off the one I bought when planting. I stuck it in a pot and it took.

What about 'Mariesii'?

Sarcococca?

I ended up with Variegated Ozmanthus and Lemon Cypress. I wanted something that would brighten up that space in the winter.