I thought the N900 had a native FTP command. Maybe not. Never tried until after I had already installed some FTP clients.

I personally think N900FTP is good. I think gFTP or whatever had more functions, but it wasn't hildonized, thus not at all finger friendly (and in some ways a bit stylus unfriendly). N900FTP, however, I find to be just fine. Is there anything specific you don't like about the currently available FTP clients available?

They are, if I'm not mistaken, both open source, so if you or someone you can ask has coding experience surely you could create a tweaked UI version to your liking?