Like asking whether the 1979 Corvette is better than the 1977 model.
They're both old enough that the mileage and condition are far more important than the model year.
Or the suffix letter F or E.
The F model is newer.
If it had an odometer, you could judge the mileage that way.
I should post a pic showing the most-likely mileage indicator. A pair of power resistors is under the driver-tube socket. You have to remove the bottom cabinet cover, then the shield under the tube socket. Finally, there is a small pc board with trimmer caps under the driver-tube socket. If the two power resistors under that board are toasted, it's a high-mileage radio.
And if they look fairly undamaged, the radio is a low-mileage specimen, and a good bet to restore.
But it's still the radio equivalent of a late-70s 'Vette. Even with low mileage there will be age issues, and parts that pretty well have to be replaced if you want to rely on it.
And if the mileage is high, or the miles were fairly hard, the list only gets longer.
Electrolytic capacitors, sure. Relays, probably. Tubes, maybe. Swollen, cracked plastic-film capacitors, missing AM-receive filter, bad clarifier switch, worn-out fan motor, the list can get pretty long.
But hey, if was a 'Vette it would need every hose, belt, seal, gasket and bushing even if it only had 5000 original miles.
Just remember, it's only money.
On the other hand, you could just jump into your handy time machine and go back to 1979 and get a new 101E for 600 or 700 bucks.
Just check the dates printed on your cash before you go. Wouldn't want to get locked up in 1979 for counterfeiting.
Oh, and yeah. The "Z" radio is a whole different design. Not so good on AM. And the "ZD" is just the analog-dial Z model with a digital display.
73