In general, what I appreciate from old shows I liked and have on DVD (of VHS) is the much better script writing... Naked City, Route 66, Maverick, Run For Your Life, Gunsmoke, I Spy, The Virginian, Ben Casey, Outer Limits, Dr. Kildare, even though they usually kept to the conventions of the era, seem much better scripted than even the better shows of the 21st century, althought these later ones, of course, are much better produced. Old times shows depended a lot more on great dialogue...