English (or seedless) cucumbers make an excellent choice for a salad as there is no need to cut them in half and remove the seeds first. Garden cucumbers have more prominent seeds in the center. They will also work just fine in this salad, but you may want to halve the cucumbers and scrape out the seeds with a metal spoon prior to eating them. The seed aren't harmful, it's more a matter of personal preference whether you choose to remove them or not.