Choice of FTP clients has long been a minor religious war among Mac users. I stopped having strong opinions on this a couple years ago when I realized that transparent, read/write FTP/SFTP should really just be built into the OS. Apple’s KEEPING ME DOWN again.
Anyway, somewhere along the line I switched from Interarchy (which I had relied on since “Anarchie” days) to David Kocher’s Cyberduck. There’s no doubt that Interarchy is the more powerful and mature program. But what I need, and what most people need, from this type of program is fairly simple. It’s a graphical client, after all. There are plenty of freely available ways to accomplish more complex file transfer magic tricks – notably rsync and friends. Cyberduck does support the ODBEditor protocol, also known as “Edit With” – this lets you open a file from your FTP client directly in editors like BBEdit, TextWrangler, TextMate, SubEthaEdit, and Smultron that support the protocol. I use this feature pretty heavily.