Like people, they are the ones that are craggy and gray. This is not the time for nostalgia. The old gray ones usually have weak spindly growth on them and are in the way of brand new canes that are now only a gleam in the bud union's dormant eyes. Use your loppers or handy pruning saw and cut the old buzzards off flush with the bud union. If It's In the Way, Cut It Away.
New growth needs room and the ideal plant grows out from the center.
Identify any canes that cross directly over the center and cut them off with your loppers or pruning saw flush with the bud union or, as is more generally the case, flush with the cane from which they have decided to grow in the wrong direction. Also, identify any canes that are seriously crowding each other. If they are not too close you can wedge them apart with a piece of stem cut from the plant. If not, cut them out with your loppers or pruning saw, again flush with the bud union or the cane from which they are growing. The relative merits of severe versus light pruning are debated at length in the rose literature.