The Spot Hogg sights all have the same pin setup and ring assembly style.
The Right On is the bare bones sight. Each pin is individually adjustable up/down as well as in/out. There is a gang adjust, however you loosen the bolt, nudge it over a bit with your hand then tighten back down.
The Real Deal offers a micro adjust for both the vertical and horizontal gang adjust.
The Hunter Hoggit adds a better gang adjust mechanism (worm drive) as well as 3rd axis adjustment.
The Hoggit is the same as the Hunter Hoggit but offers the adjustable sight bar.
I would say that the Hunter Hoggit is the sweet spot between value and features. The 3rd axis adjustment becomes very important for your up/down hill shots.
My personal preference is the Hoggit. I prefer my sight a little farther out than the Hunter will allow. It also makes it nice to remove the sight as you only have to loosen one bolt.
One thing I can tell you for certain. They are absoloutely bomb proof. You eventually may "want" to buy another sight, but you certainly will not ever "need" to. I have accidentally stepped on mine (full body weight) and it simply didn't care or move. They are also a first class company to deal with.