Used FlashFXP for years but do run into the odd problem when instructed to upload files in BINARY mode. Even if you go into the options and select BINARY as your upload method it still transfers files in ASCII.
I could go further into it but it is too much hassle
But on this point i still do use FlashFXP as it's what i'm used to and works great other than the problem above. Did try smartFTP but really don't like it and it does seem rather slow.
Gonna check out some of the others mentioned here