I really like the two Rockwell planers. Ive owned differen brands of planers over the years but I've never personally owned a Rockwell, but both machines look to be in good shape.
Points to consider:
Which machine is the oldest?
Do both have a vacuum attachment?
Are both 220 volt?
Are the planer knives in good shape?
Does the seller have the original manual for the machine?
These machines appear to be heavier made than the lightweight portable machine sold at the big box stores. Could be a great value depending on the price.
Don't forget to Check the switch and the cord.
If you don't have time to do it right the first time, when will you have time to do it over?