My Choice FTP and SFTP Clients
With OS X, I use the command line "ftp" and "sftp" for all my file transfer needs. I am using OS 10.1.5 and it comes prepackaged with both command line ftp and sftp included.
Some quirks I discovered with OS X.1.5's "ftp" is that when operated through a NAT -enabled DSL router, I need to specifically use "passive" mode to avoid locking up the terminal. Also, with my company's firewall, "ftp" just plain won't work with some hosts.
OS X.1.5's "sftp" works pretty well for me, but for large files, I miss ftp's hash feature where you see the # mark printed to let you know that the transfer is alive and get a sense of how fast things are going.
In my pre-OS X days, I used Fetch a lot, and also tried Netfinder.
I tried WS_FTP before on the Windows side, but thought it "overkill" for what I need to do. (I have also used command line ftp and tftp "Trivial File Transfer Protocol" clients in the DOS world... very simple tools, but they get the job done.)
Like many of you, I think porting more pro-level FTP clients to OS X can't hurt. If you don't like it, don't use it. It's not like it's crowding out your favorite FTP client or do you any harm.
Personally, I would like to see OS X Finder incorporate FTP and SFTP just like it handles iDisk and AppleShare volumes from a GUI perspective.