I vote for the 240. My favorite. A little background on that: the 240 is the same as the British GPMG, as per Irish's video, above. The 240 is a bit more high speed then the GPMG because, as with all things, the US bought it and stuck a rail on it and some awesome high speed gear etc. The GPMG ("Gimpy" - pronounced with a J) has been around "forever". It was used in the Falklands in 1982. Back then, the deal was that in a Para Battalion, there was a machine-gun platoon which specialized in SF (Sustained Fire) use of the GPMG, using the tripod). At section (squad) level the GPMG (or "Gun") was carried in the dismounted role by a gun group of a N0. 1 and his No 2. Back then, the rest of the section was armed with the British SLR, which is the FN FAL. The gun was deployed to a flank while the riflemen carried out the assault.
With the advent of the SAW (Minimi) at British section level, there is less need for a 240. Each fireteam has a SAW. However, what I used to find useful is to either attach a two man gun group to an eight man section to beef up available firepower, or alternatively to have a gun group, possibly two, at platoon level. These gun groups can then be deployed to influence the battle. Nothing better than the beat of the "gimpy" going in as fire support.
Brit Paras were always sticklers for how the gun was carried. No sling over the neck, the sling could only be over one shoulder so the wepaon could be brought into action rapidly. The Gimpy was carried extensively dismounted on patrol.
