Hi Jen, hope you don't mind my 2 cents.
Using GEDCOMs to populate WikiTree is a personal decision based on your personal likes and needs. I add to WikiTree almost exclusively by GEDCOM. Like you, I have 1,000's of names across various trees on Ancestry. And like me, you probably not only have blood kin in your trees, but also the families of those our ancestors married into.
First of all, uploading a GEDCOM file to WikiTree is not like loading one to Ancestry or many other sites. You have to individually add each name to WikiTree on a one by one basis. WikiTree does not permit duplicate Profiles of a person. If you find someone has already entered a name in your tree(s), you then share the connection with that Profile. Hence, the One Global Tree. This is the reason for the one by one basis of adding folks.
I suggest you create a new small tree on Ancestry of say 30 to 40 names and export that as a GEDCOM file. Then try theGEDCOMPare upload utility on WikiTree. Remember, this will not auto populate your tree on WikiTree as on Ancestry. You will have to add each by themselves. You can then see how the data from Ancestry is loaded to WikiTree and what it looks like in a Biography. Trust me, they are not the prettiest of Bios and will need a little work to make them more presentable. You still work on each Profile to make it the way you like.
See if using GEDCOM files is for you. Here are a few pages I think all who want to try using GEDCOMs should read.
https://www.wikitree.com/wiki/Help:GEDCOMpare GEDCOMpare basic help
https://www.wikitree.com/wiki/Category:GEDCOMs A compilation page of various information pages on GEDCOM files and WikiTree
https://www.wikitree.com/wiki/Help:Uploading_vs._Importing Why WikiTree is different from other sites regarding GEDCOM file uploads.
https://www.wikitree.com/wiki/Category:New_Member_How-To Self explanatory and I include some of the help topics below as well.
https://www.wikitree.com/wiki/Help:How_to_Edit_a_Profile How to Edit the text on a Biography and add sources
https://www.wikitree.com/wiki/Help:Editing_Tips Some more tips on Biography editing.
https://www.wikitree.com/wiki/Help:Biographies What can be included and proper order
https://www.wikitree.com/wiki/Help:Sources Extremely important on proper citing of sources on WikiTree
https://www.wikitree.com/wiki/Category:Styles_and_Standards List of all the WikiTree Profile standards and style
https://www.wikitree.com/wiki/Help:Communication_Before_Editing A good thing to do before Editing an Existing Profile
https://www.wikitree.com/wiki/Help:Uploading_vs._Importing How gedom files are loded to WikiTree
https://www.wikitree.com/wiki/Help:Ownership_and_Control Sharing Data Basic
https://www.wikitree.com/wiki/Help:Project_Protection Project Protected Profiles or PPP files. Certain Protected Profiles.
https://www.wikitree.com/wiki/Help:Pre-1700_Profiles Certification For Pre-1700 Profiles IMPORTANT
https://www.wikitree.com/wiki/Help:Pre-1500_Profiles Certification For Pre-1500 Profiles IMPORTANT
OK, maybe more than a few...LOL Fortunately, most are quick one page descriptions.
One thing I strongly suggest is to look at as many Profiles on WikiTree as you can to see the variations in style members use to create their Biographies. Here is a good page to start: https://www.wikitree.com/wiki/Help:Examples Better to look before you leap and to get get off a good footing when creating Profiles.
So enjoy and and add the way you want to. All the best,
Oh, one more thing about GEDCOM files from Ancestry. Some Social Security related sources may include the SS Number of the individual. Please be sure to remove them once they have been imported into WikiTree for good Privacy measures.