For me, the best airline to move to T2 would be Thomas Cook.
They have about 16-17 aircraft based at MAN, but up to 8 of those are either long haul (thus not taking up overnight stands) or they are aircraft either arriving late or departing early, thus not taking up much stand time either. This means that they roughly match what Monarch had overnighting at MAN and thus less requirement for any split ops scenario.
They are probably going to move over to T2 eventually anyway to avail a possible USPBC, coupled with the fact the 'satellite' at the end of C-pier is likely to be the first part of T1 to be demolished anyway, it seems the best fit.