I used to use leechftp, I had some problems with it - I hate how it has "failures" and gives up on certain files, and it always gets me banned from ftp servers because it hammers them.
before I used leech, I swore by flashfxp, great program. only thing was.. I had an. *ahem*.. ahh not-so-legal registered copy, and it kept warning me that it knew I had an illegal registration # and as I read this, flashfxp was calling the swat team to my house to pin me to the wall and blow my brains out or something. 🙁 basically it was just annoying.
but since, I've tried it again and I don't get that crap. Yet.
one thing I liked about cuteftp and leechftp, that flash doesn't seem to have, is storing of ftp server "favorites" with my account info, etc. there is just a history feature on flash, but that doesn't help me much