What cargo airplanes can transport fully assembled large turbofan engines?
Engine nacelles are part of the aircraft and not the engine. I think you're asking about fully assembled engines.

Oversized jet engines are usually transported by road when possible; in case air transport is required, the Antonov An-124 'Ruslan' is your best bet. It is the only aircraft capable of transporting engines like the Engine Alliance GP7000 and RR Trent XWB.



Image from antonov.com

For smaller engines (or partially disassembled ones), other aircraft like the Boeing 747F and A330-200F are used.

Interestingly, this filing with US DoT shows the An-124 being used to transport GE GEnx engines from Rickenbacker airport to Seattle to ensure smooth production in Boeing factories.