In real life I use NetFinder. It’s not actually real integration of FTP into the Finder, and MacFusion is, but MacFusion is just too damn slow. And NetFinder does a really good illusion of integration. It looks like the Finder. It mostly behaves like the Finder.
It’s out of date and underfeatured and I would not pay shareware for it nowadays, but since I already did a long time ago and it still does everything I actually need an FTP program to do, it’s what I use.
(I still have Fetch around as well but no real use for it)
I use “FTP For A Buck”. It’s very basic and doesn’t have many frills or extras but it’s fine for what I need.
Heck, I write webpages with Notepad and use MS Paint for graphics.
Another vote for FireFTP. I’ve never noticed it to be buggy.
Sometimes, though, old-school FTP-ing is the best way to go (depending on where I am), and I dust off my “put,” “bin,” “del,” etc. commands.
If you’re not doing anything too elaborate, and if your primary goal is to transfer files to and from your XP or W98 system, why not just use Windows Explorer? You can just type the ftp server name into the navigation field at the top of Explorer, and cut, copy, and paste files between local and remote directories the same way you do between directories on your own machine.
I suppose there are some cases where it’s not customizable enough, and it’s not really scriptable, but for my very rare use, it does the job just fine. You don’t even have to type in the ftp server name more than once, since Windows Explorer uses the same bookmarks as IE.
I’m a little rusty on FTP in OSX, but it seems I remember you can do pretty much the same trick in the OSX Finder.