Filling in some years here that I recall:
RCA rectangular color sets from 1965 (CTC17) thru 1968 (CTC35) made a great picture but you need to reduce the flyback load by using the "high line" tap on the power transformer and adjusting the efficiency coil. I had to condemn a good many when the customer said "it looked great, then quit" as I pulled off the back, noticing the baked-fly stench as I did so.
The CRTs seemed average in these years. The 1969 and later tube TV's (CTC38, 39 and some others) were not so great but as Zeno mentioned in post #7, the all-transistor stuff even before the XL100 (1973?) was pretty decent. That is where quality was going while the cheaper tube TVs were winding down.
The early 1970's had a modular series called "accu-color" and the chassis I recall CTC52, 19" using a one-gun CRT, while the bigger screens were still delta-gun. This pre-dated the XL100 and the smaller sets' one-gun CRT's were not easy to rejuvenate ,if at all.
About the same time, a cheaper smaller screen tube chassis was the CTC53, which I think still had a delta tube, perhaps the last of its kind. All told, you got what you paid for.