Gear reviews are usually full of technical jargon and concepts I don't understand. You will find none of that here.
Instead, enjoy the ramblings of a 30-year paddler who enjoys all the technical advantages he can feel while using the product. I began paddling with heavy, 90-degree-feather, symmetrical paddles that were short on glitz and long on endurance, much like those of us who used them. As the paddles began to get better, I had to try the new ones in search of something that wasn't a club. Boy, have they gotten better!
All the paddles in this review are light-years ahead of those early offerings, and each would be a fine paddle in the right hands.
Buy the best paddle you can afford. You will thank yourself every time you use it.
What I look for in a paddle is a good grip, balance, stable feathering, a light swing weight, durability, and the right amount of stiffness and power to do the job at hand. High- and low-angle paddles each have their better applications. I typically paddle with a shorter, high-angle, stiff, larger blade in a single kayak because it gives me quick acceleration and response when playing in surf, current, or rock gardens.
I switch to a low-angle, longer, more flexible paddle with a smaller blade when I'm doing a trip in a heavily loaded kayak, especially tandems. This saves a lot of abuse on your shoulders, as the smaller blades have less bite than the larger blades, which transfer all that weight/stress directly to your body. You end up taking more strokes with the smaller blades, like shifting to a lower gear on a bike--more revs, less stress.
I also use mostly bent shaft paddles, for two reasons: they have a more well-defined oval grip, and they keep my wrist straighter during those times when I need to hang on a little tighter, like when I'm rolling or bracing. I also have become partial to the foam-core blades on the higher-end paddles for two reasons: they are floaty, like wood, and the thicker blades make for more predictable feathering action when I'm doing all the fancy draw strokes, or just saving myself with a firm sculling high brace.
Many of these paddles have some kind of ferrule that allows you to adjust the feather and/or length. If you paddle different boats, or like to switch between high and low angle, you may find these of interest. On the adjustable-length shafts, there is an extended inner ferrule with 1-cm markings, along with feather-angle markings. You slide the paddle until you get to the length you want, turn it to your feather angle, and lock it in place. I am a big fan of simple ferrules, i.e., no parts or tools to lose, and like to have a few years on more complicated mechanisms to see how they hold up before I invest.
All the above being said, the most important thing you can do for yourself is get in your boat (or one of similar dimensions) and try out bent and straight paddles in different lengths, blade sizes, and materials. Brace, draw, and scull with the paddles to check the predictability as you slice them through the water. You may find that you don't need to spend the big bucks to find a paddle that suits your style of paddling. You will also see why the more expensive paddles may be worth the money to you. Buy the best paddle you can afford. You will thank yourself every time you use it.