How dapper you look depends on how much you want to spend, in most cases. There are a few independent manufacturers making cute rain capes for under €100 that are marketed as being designed for cycling and hiking, but we can’t verify the quality of these items.
Standard yellow-rain-jacket-type capes exist and are a smart choice for safety reasons, what with their bright colors and all, and they’re often the least expensive. But better-looking options are certainly out there.
Cycling capes are longer in the front to fit over the handlebars and provide a big waterproof tent with good ventilation beneath it.
Rain capes for cyclists are quasi-ponchos, smaller and sometimes longer on the front. They're supposed to go over the handlebars and seat. Depending on the cape design, often it will obscure your lights, particularly on the handlebars. You may adjust for this, such as mounting your light to your helmet instead.
A cape without a rear cinch will fly up in the wind. A waistband and hand loops keep them from flapping in the wind. A hip tape at the back part prevents blowing up and fluttering in the wind.
In the breast pocket you can accommodate small items, or pack the rain cape into it. The breast pocket is often designed to be a belt pannier at the same time. A volume-adjustable view window hood prevents visual field restriction.
With the driver-hand hold loops, you can ride a bike comfortably while keeping the cape down in the front. Elastic loops built into the front of the rain cape that go over your wrists, and in the back there's a waist loop to keep the rain cape in place in windy conditions.
A cycling rain cape with sleeves keeps you warmer, but can make you sweat more. It is generously sized and longer in the front for maximum coverage. The fabric may be heavier than the usual nylon and polyester ponchos. Some have a solid plastic rain visor on top of the hood.
Apart from cycling you can use long sleeve capes for other sports like canoeing, boating, rain walking, or swimming.