Today there are not a lot of quality manufacturers building small panels suitable for marine use. Most are building panels in the 100+ watt range these days. For small panels I have been installing panels from SunWize and, while not the quality of a Kyocera, they have been of decent quality. Some manufacturers specifically exclude "marine use" in their warranty so its best to check with them before you buy a solar panel for a marine application.
Mono & Polycrystalline:
These are by far the most long lived and efficient solar panels per sq in. These are almost always rigid panels in an extruded aluminum frame with tempered glass not an EVA skin. These panels are more prone to shading issues but also have about double the output per sq in when compared to most inexpensive flexible panels. Glass covered arrays also do not suffer from a flexible EVA cover deteriorating from the sun's UV rays and can often offer better UV protection to the cells over a long duration.
While Dupont has really pushed the envelope on EVA films, and it has gotten better, a quick look at many of the warranties will show a difference between flexible and rigid panels. Kyocera for example warrants their panels for a minimum of 95% output for 20 years. Some EVA panels are warranted at 90% from year 1 and at only 80% output starting at year 10, the Kyocera's are warranted at 95% output at year 20, and they've actually been around longer than their warranties have been in place. Something to consider..
Amorphous panels are made differently and by their nature require nearly double the surface area to equal the same watts in a mono or polycrystalline panel. They are upwards of 50% less efficient than a good mono or polycrystalline panel.
In the marine market many of these panels are made to be flexible which can make them even less efficient. The combination of a flexible EVA lens, that can slowly degrade in UV, and the fact that one side may not be aimed at the sun if "flexed", say over a boom, can often mean very little output for the sq in you have out there. Even in perfect conditions you still need a lot more space for an amorphous panel than you would a mono or polycrystalline panel. Yes they can be convenient but you'll need to weigh the benefit/space/cost & efficiency issues too.
While there are some high efficiency flexible panels that are not amorphous, such as the Solbian's made in Italy, that compare in output to the rigid panels, they are quite costly compared to rigid panel at nearly triple the cost or more. Ganz also makes some efficient smaller panels but again the price is about double or more what a rigid panel costs. If that convenience is worth it, then they are a good deal. These semi flexible panels can also save on installation costs as the "support" frames needed are smaller and lighter and less costly to develop.
The neat thing about the Solbian "semi flexible" panels is they can be sewn right into a bimini top and have no sharp edges. Some of the solo round the world racers are using this technology and, good for us, it will eventually trickle down. Due to the flexible nature however they can possibly suffer from UV degradation faster than a comparable glass encapsulated panel.
Amorphous panels do have one benefit and that is they are less prone to shading issues than a mono or polycrystalline panel. This "benefit" however can be quickly dwarfed by the real estate needed to equal the output of a mono or polycrystalline panel.