I've generally gravitated towards dipole antennas for HF, not paying a lot of attention to Verticals. While I do believe dipoles are generally more flexible, in that they can be used to communicate across a range of distances from local to world-wide, there are some advantages to deploying Verticals, especially if you're deploying with a vehicle or trailer equipped with one (or more).
I've covered Near Incidence Vertical Skywave (NVIS) antennas before, basically deploying a dipole close to the ground. The advantage of the NVIS dipole is the ability to create a local or regional cone around the transmitting stations in the 200-400 mile range. Flying the dipole low causes radio signals to radiate more vertically, and are reflected downward rather than over the horizon. Think a water hose pointed at the ceiling of a room - the water will bounce off and scatter all over that room. Take that same dipole and raise it high (at least 1/4 wavelength above the ground) and you can now communicate world-wide.
The NVIS dipole will radiate with a takeoff angle of over 60 degrees, while a non-NVIS dipole will have a takeoff angle of closer to 25 degrees, and as low as 15 degrees. One thing we have noticed, is local communications, 0 to 30 miles, with dipoles is very hit-and-miss. Even with NVIS, the immediately surrounding areas are usually overshot by the reflected signals. NVIS for local communications can work, but, as I said, it is hit-and-miss.
Verticals, on the other hand, naturally radiate at a low angle, so the "skip" is long. But verticals, because of the low takeoff angle, also provide good local ground-wave propagation. 160 Meters is a really good ground-wave band, but a Vertical antenna supporting this band is ungainly at best. 80 Meters and 40 Meters are also "ground wavy", but not as good as 160 Meters. Still, a ground mounted Vertical can provide good local propagation out 20-40 miles. As the bands go higher in frequency the local propagation distance rapidly diminishes.
A ground mounted Vertical will radiate with a takeoff angle around 25-30 degrees, while one raised on a mast will radiate at 10-15 degrees, outperforming even a raised dipole in that respect. Both ground and raised verticals will work well for DX, but the raised Vertical will more easily reach intercontinental distances. Raised verticals also have the advantage of clearing local noise for a cleaner signal coming in.
In terms of deployment, dipoles can basically be "thrown in the trees", with no need for masts or other mechanical supports beyond rope - if you have trees around! On the other hand, a Vertical can be mounted on a vehicle or deployed using a ball hitch. The West Georgia Amateur Radio Society (WGARS) has included a mast in their communications trailer, allowing deployment of raised Vertical antennas as well as deploying inverted-V dipoles.
So, what does this mean for EMCOMM? Well, it would seem using ground mounted or close-to-the-ground Verticals would be preferable for local communications (0-30 miles) on HF ground-wave frequencies, 160-60 meters while still offering success at medium range communications (400+ miles). A NVIS antenna would probably be best for communicating in and out of a disaster area (ranging 30-400 miles) on 40 or 60 meters daytime and 80 meters night time, while a non-NVIS dipole or vertical antenna would be best for more distant communications on around 20 meters during the day and 40 or 80 meters at night.
Keep in mind, that for local communications on a ground mounted Vertical, all stations would need to be using the same configuration for optimal performance. How your signal is oriented (Vertical or Horizontal) ceases to be significant once the signal skips.
