Most reliable color set I've got is a 1967 Airline(bottom left).
That set was on the second floor living room of a mom and pop podetrist's(misspelled) office/home. It was used regularly for years, and it actually still worked fine there when I bought it. It is a Muntz made RCA clone. Several tubes are replacements but it otherwise looks like nothing was replaced. I've been running it occasionally as found only with some adjustments since then...Though I really need to fix or replace the bad vertical centering control so I can get good purity and vertical geometry without the bottom 1-4" of the screen not being scanned.
The 1965 Philco next to it would be runner up. It only needed the internal horiz. osc. adjustment tweaked....Though I did replace some caps to improve it and make it safer. It does have more factory original tubes IIRC though...