Answer: Although Photinia should be hardy in your area, I would hesitate to use it due to its susceptibility to problems such as shot hole fungus which is disfiguring and also potentally lethal unless controlled with routine spraying. It would also require frequent pruning to stay small enough.
In terms of laurel, you might be thinking of Cherry Laurel (Prunus laurocerasus) however this is also subject to shot hole fungus and would require pruning similar to the Photinia. You might look into the dwarf forms, however, such as "Otto Luyken" or "Schipka." These will grow best in a soil that is organic and evenly moist yet well drained.
Instead, you might look into using boxwood which would give a similar look to the holly you are removing and is not susceptible to black root rot, according to the following information sheet from Virginia Cooperative Extension. (You may need to cut and paste the complete url into your browser to make it work correctly.) Boxwood does require a well drained soil to grow well.
I would also suggest you consult with your local county extension to verify that black root rot is actually the cause of the decline. They, and your professionally trained nursery staff, should also be able to help in analyzing the growing conditions where you wish to replant your hedge (sun, soil type, wind, possible salt from the road, etc), and then identify plants that would thrive there. Then use the one you like best out of those.
I'm sorry about your Japanese hollies. Good luck with your project!
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