Does a complete, modular, portable and easy to extend MITM tool actually exist?

If your answer is "ettercap", let me tell you something ...

• ettercap was a great tool, but it made its time.
• We've found ettercap filters to simple not work in many cases as they are
  outdated and also haven't been maintained as there aren't as many low-level C
  programmers interested in maintaining it.
  ettercap is freaking unstable on big networks ... If you've tried to use
  ettercap's host discovery feature on any large network you'll see it simply
  can't scale well.
• Yeah you can see connections and raw pcap stuff, nice toy, but as a
  professional researcher I want to see only relevant stuff.
• Unless you're a C/C++ developer, you can't easily extend ettercap or make your
  own module.

Indeed you could use more than just one tool ... maybe arpspoof to perform the
actual poisoning, mitmproxy to intercept HTTP stuff and inject your payloads and
so forth ... I don't know about you, but I hate when I need to use a dozen of
tools just to perform one single attack, especially when I need to do some black
magic in order to make all of them work on my distro or on OSX ... what about
the KISS principle?

So bettercap was born...