ws_ftp is very comfortable, especially because it inserts a BHO into IE, so when you click on a ftp link, ws_ftp tries to download the file, instead of internet explorer. if ws_ftp notices that the destination is a directory and not a file, it will open the main programme and log in automatically. I think we all know that IE cannot handle ftp sites, so this programme is really valuable.
apart from that ws_ftp itself is comfortable, even if the newest versions since version 7 have become worse (e.g. the transfer manager is in a separate window, and one has always switch between the programme itself and the transfer manager; this was better solved in previous versions).
anyway, this programme is very reliable, it works on servers, where flashfxp gives up.
cuteftp is second choice, but personally I like ws_ftp better. nothing objective about this, just my personal preference. actually ws_ftp pro and cuteftp pro 2 are equal.