I use RootsMagic 7.
You can download a gedcom file for either ancestors or descendants of an individual fairly easily. When you do so make sure the file extension is “ged”. Sometimes it is saved with the “txt” extension. If that is the case your software will not recognize it. Just rename the file and it should then import.
Be prepared for some work to cleanup the file.
There are some WikiTree specific fields that are exported, you can keep or remove these as you choose.
If the WikiTree profiles have used the middle name field, these will not be imported because it is a non-standard gedcom field.
You may get a number of unconnected “Anonymous” people because of privacy settings.
If a person is not connected to both of their parents (ie, they are erroneous half-siblings) you may get phantom spouses.
A big part of the formatting in the bio narrative is lost as it gets turned into wiki markup or html code, with the result that the bio is hard to read.
Sources remain in the bio and are not put in the gedcom source fields due to how WikiTree is set up. These get the markup/html as well.
One good point, at least in RootsMagic, is that the profile ID (eg, Smith-123) goes into the RootsMagic address field as the terminal part of the WikiTree url for the person. I usually make these a source as they are then easy to see and will print in the reports.