I would say you should decide which to keep by deciding how much time you can or want to spend working on your car.

I had a 90 740T for several years and it needed maintenance or repairs frequently, as I undid a decade of poor/no maintenance. It's parked, after an engine swap didn't go so well.

Now I'm driving an 84 244DL. No ABS or Airbags. It's noisier. But it starts every time, and aside from my freshening up a few things when I bought it to get it running right and oil changes, it has asked nothing from me.
It needs its overdrive seals replaced, tires, and tie rods, and is quite loud doing 3000rpm at 60mph, but it gets me around just fine.
There is a lot of maintenance I could do to it, but that is waiting for summer.

I live just shy of a mile from my school, so I've just been walking there and taking the car to get groceries.

The third option you didn't mention is to keep neither. Just food for thought, but some cars aren't worth fixing up money-wise, thought they may be other-wise.

Good Luck