I would think the ideal weapons in today's world might be an unfortunate fall down the stairs or an unexpected suicide...the crime being more sophisticated than the actual weapon. Also, suppressors have come a long ways from the prohibition days. Realistically, anyone with some time and access to a machine shop could put together an effective suppressor.
Maybe an IED if a statement must be made (e.g. the chicken man).
To make things even (caliber wise atleast) If I was offered a H&K UMP in .45acp then I would still take the Tommy Gun.
Pulling an H&K out of a violin case just looks silly.
sure there is good stuff now
but yea an old tommy and ammo was cheap then! heck yea!
jake