I use FTP Surfer nice and simple plus Free. Are you talking about Filezilla? If so thats a good one as well and free but I had some problems with it (I forget what though).
I use smartFTP however sometimes when I upload larger image files it puts streaks of color across them. Probably a problem with my PC though using the program as it hasn't happened on any other FTP program. And I've installed/uninstalled smartFTP numerous times with the same results occasionally.