J-Prop
I chose the J-Prop for a variety of reasons. Ease of installation (no assembly to speak of), external pitch adjustment, construction and material, and to some extent price. The prop comes fully assembles and all you need to do is slide it on the shaft (with a proper test fit first), tighten the nut with the supplied wrench, install and tighten the lock nut with it's supplied wrench, install a retaining ring and the zinc, and fill the hub with grease with the supplied grease gun. Set the pitch and your ready to go. The prop has a small number of parts and is made of aluminum-bronze and stainless steel. You probably have to modify your prop shaft so that the threaded portion is 1-1/16" long. This is true for the other feathering props as well except perhaps the Martec.
J-Prop Web Site

Max-Prop
The Max-Prop is the most established. It is a wonderfully engineered product with apparently excellent support. But pitch adjustment requires disassembly of the propeller and that requires haulout. The pitch increments are finer then the J-prop by about half and that is appealing to me. And you can get an externally adjustable version for an extra $1,200 or so. But the ease of pitch setting on the J-Prop seemed more useful to me. They priced about the same.
Max-Prop Web Site

Martec
The Martec is made of stainless steel. It's a good stainless for props but from what I have read I decided bronze was a better material. The steel blades on the Martec are thinner then the bronze props but the hub is larger and that probably negates any drag improvements. The pitch settings on the Martec are made with a set screw. It is continuous (the others are discrete) and you can set a different pitch for forward and reverse. I like the idea continuous pitch adjustment but it will not be as repeatable as the discrete. But maybe that doesn't matter since what you will know is that you need more or less pitch. Returning to a previous setting may not matter that much. The set screws and lock nuts are pretty robust but I did wonder about the security. There can be a lot of vibration and if it came loose there goes your pitch setting. I'm sure the Martec reps would say that's not a problem, they are very secure, and they're probably right. The Martec is also the least expensive of these props at about 75% the price of the j-prop.
Martec Web Site

Autoprop
The Autoprop is a different machine from the feathering props. Each of the three blades is free to rotate on an axis perpendicular to the shaft. The blades find there pitch automatically depending on the load. In tests the prop does very well and provides a higher top speed then the others. There would be an advantage to the automatic pitch when motor sailing too. But I was wary of the blade independence and the continuous wear on the bearings. On a boat with a prop shaft that is angled down (like mine is) the blades would be changing pitch continuously for every revolution. That seems like it would lead to a lot of wear. Perhaps on an installation with a horizontal shaft this would be improved. The Autoprop is also about 25% more then the j-prop.
Autoprop Web Site

Gori
The Gori three blade folding prop is a beautiful thing to see in action. Really slick. It's sort of a hybrid between feathering and folding as the blades swing around for reverse giving the same profile advantage of the others. And it is really something to see. It's hard to describe the action but the blades swing on an axis perpendicular to the prop shaft. When you go to neutral they fold up like a conventional folding prop. When you go to reverse the unfold in the other direction (they continue swinging from forward-open to folded to reverse-open). You really need to see it. The prop is a beautiful polished bronze. The pitch is fixed and that (along with a price about 25% higher then J-Prop) made me wary about getting a good match to the boat. The blades are also twisted as on a fixed prop, not flat like the other feathering props. This should improve performance with the correct pitch and twist. Gori will work with you to get it right and I am sure they will do a good job but I may have a re-powering in my future and the prop might no longer be right. The others can simply be adjusted for the new pitch requirements. And the Gori rotates on exposed gears. They are very large but it seems conceivable that some barnacles could get in there and foul things up if the boat was lightly used. This could cause the prop to jam or it could accelerate the wear on the gears. But you gotta se it work. Really slick.
Gori Web Site