If you choose Display Name as an option, you may not get the results you want depending on how your 140+ users choose to set their display name. Display Name is one of the settings each user can control within their profile and WordPress offers several choices:
- Username
- First Name
- Last Name
- First Name Last Name
- Last Name First Name
Because each user could choose a different setting for their Display Name, if you set Email Users to use Display Name, you could potentially end up with a list that doesn’t appear to have any rhyme or reason to the ordering.
Display Name would be the last choice I would pick. Personally, I almost always use Last Name, First Name (username) with Email Users as I find it the easiest for locating users. I’ve used it extensively with our swim team site which has 300+ users registered.