It depends on what you are going to do with it. Free air represents how fast it will pull the air out of the vac bag. You also need enough free air capacity to overcome any leaks
in the bag or seal tape until you can locate the leak. I have had large, complicated parts
that I had to put both my pumps on them in order to get enough vacuum to be able to find the leaks.
The level of vacuum may be less important, I think some of the pros use a lower vacuum than either of the pumps you are looking at.
It also depends on the size of the piece and how air tight everything is. A big pump can give you good results even with some leaks, a less powerful pump may not.
Either of these pumps should enable you to make reasonable sized pieces of several square feet or more.
Again, if you let us know what you plan to do with a vac pump we can probably give you a better answer.