I'd say Wednesdays always tend to have a nice mix of aircraft coming and going at MAN. You always get the afternoon lull most days around 2pm when all you usually see is BA regional and Air France always seems to be about.
If you get there early enough you'll catch the morning charters - Air 2000 seem to have the major prescence now during the day. Also, Qatar Airways departs around 10am, along with the usual long haul flights, although SQ have dropped their flight on numerous dates.
Aswell as thats, there's Emirates, and Air Jamaica in the afternoon.
Regards