Potted roses or bareroot roses are the best buy in the long run. Be sure to look for canes that are healthy and of a size that will support new growth and the blooms to come. Boxed and bagged roses are less desirable because their roots have been sheared to fit their containers. The rose will not flourish without a substantial root system to absorb the needed nutrients and support new growth.
Some nurseries wax their roses to prevent the canes from drying out.
Removing the wax is tedious and may damage the growth points on the canes. Therefore, these roses should be avoided. Be sure to buy from reputable sources. No roses are guaranteed beyond the first growing season, so choose carefully.