I switched to yafc from lftp years ago and never looked back, so I can't really compare it to newer versions of lftp. IIRC the biggest wins at the time were context-sensitive tab completion, including support for remote paths, and automatic bookmarking with saved passwords (optional, of course). FTP sucks, yafc makes it tolerable.

clex's approach to file management is by complementing the command line; you can generally use it as a pure CLI and it stays out of your way unless until you need to find or select a path. Every action you perform remains on the command line, clex merely makes it easier to quickly build commands. Compared to clex, Midnight Commander (like Norton Commander before it) feels like an attempt at a graphical file manager for the terminal, where the command line is almost an afterthought.

+1 on comparing yafc with lftp