Not a Beatles expert, but there are a lot of laserdisc editions; it could be possible to find out some mono versions, so I guess laserdisc higher S/N and dynamic could be a better source, at least in theory.
The only laserdisc with the original mono soundtrack is Let It Be. Let It Be (the album) never had a mono mix (other than fold-down mixes released in some countries).
The songs on the other 4 films on Laserdisc are either stereo remixes or include the original stereo album versions.