In an open field? I'd say it's a coin toss.
- Equipment is of roughly the same quality, however the NCR is probably better outfitted for a frontal engagement.
- Legionaries are more experienced and better trained, thus would be more capable of carrying out drills and manoeuvring under fire. Well-trained and experienced troops also are less susceptible to suppression which is the key factor in 'modern' infantry engagements.
- Leadership is definitely on the side of the Legion, considering 2/3s are guaranteed to be battle-hardened veterans and capable of taking over command of the whole unit or the individual squads.
- Morale is also on the side of the Legion. It makes them less likely to become suppressed or flee. Also more likely to force breakthroughs as a result of acts of personal courage, these being a big and often underestimated factor in infantry engagements.
Given it's an open field, without cover, it'd still be a coin toss. If we were to go with a scenario that has some terrain features and room for manoeuvre and tactics, the Legion would win hands down. They simply have the better troops pound-for-pound.
