In principle, Chris, under free-space conditions, an end-fed halfwave and a dipole should radiate very similarly...but in practice, they don't. Interaction with the earth has a big effect, particularly on the end-fed antenna. The angle at which it is sloped also has a major impact, and not usually a positive one either.
A friend of mine out West had high hopes for an EFHW antenna for the ham bands that had been touted as something of a miracle, but in the end it never matched up well on any of the bands he wanted to work and the radiation angle was too high for appreciable distance. He's gone back to a basic multiband vertical with radials and gets much better results. (Fortunately, he has ample open space at his site.)
A ground mounted 1/4-wave vertical with radials or a good ground screen has the most predictable and repeatable characteristics and the best omnidirectional pattern--or a 5/8-wave for even better low-angle radiation, although it's physically more challenging in many locations. But unless the ground is sufficiently unobstructed for a wavelength or two in all directions, you'll lose some of that signal locally.
A ground plane antenna or a dipole mounted a little above the earth may avoid some obstructions, but won't necessarily have good low-angle radiation or predictable performance, unless you can get its feedpoint half a wavelength above ground or more. A quarter wavelength above ground is the worst case for take-off angle, in fact. Higher or (if necessary) lower than 1/4 wave elevation is better.
The two most consistent performers here on the prairie are K6FRC from out west in California and RY down east in Maine. At FRC, the antenna is a relatively tiny 20 meter Hamstick mobile antenna on a metal roof of a small building (a shipping container). It has the advantage, though, of a nicely elevated site with no lossy trees in the immediate vicinity. RY uses a vertically mounted dipole, suspended from a tall enough tree that its lower end is well above ground and can maintain a low radiation angle. I would refer you to the "What antenna are using on your HiFer" thread on the LWCA message board back in October for more ideas.
Moral: a relatively simple antenna, well placed, can be effective and avoids a lot of the guesswork that goes along with some larger antennas.