Keep it simple...
Straight and bent shafted paddles are very close in price. In fact some ergonomic paddles are cheaper than straight shafts. It all depends on the materials.
Bent shafted paddles have bends where your hands grab the paddle. They just help to align the bones in your wrists better. They are quickly becoming the norm.
A crank shaft paddle, bends near the blade of the paddle. This allows the blade to protrude forward, and reach past the normal range of a forward stroke.
A wing paddle has a spoon shaped blade. Very popular with the racing elite. (Wildwater racing, flat water, marathon, off shore, etc...) They provide a lot of grab in the forward stroke. It would be a bit overkill for everyday usage.
I love to dance, but who needs the music- It throws me off.