I use Total Commander for FTP. It is also the best file manager you will ever use.

winSCP

I used to use SmartFTP until I updated to version 3.0 where now they force the non-disableable transfer queue, which meant that my transfers would take from a couple minutes (prior to version 3.0) to maybe a few hours (now). So, I switched to FileZilla. I've downloaded a copy of the latest old release of Smart before the 3.0, so I have that in case I want to go back.

SmartFTP (2.5) atm.

Used FlashFXP for years but do run into the odd problem when instructed to upload files in BINARY mode. Even if you go into the options and select BINARY as your upload method it still transfers files in ASCII.
I could go further into it but it is too much hassle :)

But on this point i still do use FlashFXP as it's what i'm used to and works great other than the problem above. Did try smartFTP but really don't like it and it does seem rather slow.

Gonna check out some of the others mentioned here

SmartFTP -- great program!

CuteFTP Pro all the way. been using it for a long time.

FireFTP... nice piece of work! ;) embedded on my browser

SFTP w/ WinSCP :)

[high]* Dan high-fives Bob[/high]

Best file manager ever.