CoreFTP when I have to use an FTP client. Most times I just connect with RDP and copy and paste does the trick.
I presume your using Windows servers? Is RDP possible with Linux servers? I use WinSCP from time to time and really should get to know it better.
CoreFTP Filezilla messes with my server and I can't see any of the permission / doesn't open all the folders.
FileZilla, I used to use coreFTP but I have 4 FTP programs just incase a customer has a issue I can test the account with more than one FTP program.
I use Filezilla but it does occasionally get me banned from servers because it appears to open up more connections than some servers allow. That happens even if I set a limited number of simultaneous connections