This would be easy to determine if there were only one hardiness map. All three are valid, but be aware which map is being used in a reference or catalog since the zone number will vary. SOIL Soil type is discussed in chapter 2, but you should be aware that soil affects plant hardiness. For example, a Zone 6 plant may be hardy in Zone 5 if it is planted in a sandy loam. However, if the plant is in heavy clay, that may retain too much moisture during winter, the plant's potential hardiness is reduced.
Most references provide the recommended soil type for a particular plant.
Most Ohio soils are clay and may require amendments or special preparation before planting. Another option is selecting a plant that grows easily in heavy clay soil. Soil fertility and pH also affect plant selection and growth rate. Some plants require a regular application of fertilizer, while others survive quite well under low fertility. Likewise, particular trees and shrubs grow better in certain pH ranges.