Which car is the overall to keep for a couple of yrs? 1999 Nissan maxima, 1999 Altima, 2006 ford Taurus or 2002 buick lesabre?

All of them have low mileage as the Taurus have 69000 and the maxima have the highest of 123000. They all under 1100 bucks.

2006 Ford Taurus is only $1100 ?

None. Buy new one.

They are all rental cars - meaning they are cheap and might last you a few months, a year or even two years.
There's no way to know which one will last the longest.

Based on just what you told us, i'd go with the Buick LaSabre.

The one that is currently in the best mechanical condition. And its impossible to know that from the information given.

The mileage of all the cars is probably unknown too. You can't count on a correct odometer on old cars.

So don't weigh that heavily.

The Altima is the best of that bunch, assuming they are all in the same condition. You will be the last owner of the Buick if you buy that one.