Despite all the marketing hype about advanced features, choosing the right electric shaver hinges on one critical decision: Rotary or foil? Although the two types get you to the same goal -- a smooth, clean face or head -- they do so by very different means.
Rotary shavers use spinning circular blades, which flex in their housing to accommodate the contours of your face. Because each blade on a rotary shaver swivels independently, these shavers may do a better job than foil shavers at following the contours of your face and neck. Rotary shavers tend to be quieter than foil shavers, handle longer hair better, and offer the advantage of letting you shave in almost any direction -- up and down, side to side, or even moving the shaver in circles.
Foil shavers have oscillating blades hidden behind thin, perforated steel foils. The foils lift your facial hair (or any hair, really) up to the blades for a close shave. Most of the foil shavers I evaluated have between three to five blades, although the travel models have just two rotating cutting heads or, in one case, a single foil. The number of blades determines the size of the shaving head and, in theory, the speed of your shave.
However, bigger isn't always better. If a foil razor's shaving head gets too big, it can be hard to maneuver over the contours of a smaller face and neck. Every once in a while, you might come across a shaver that has blind screens -- for example, four foil screens but only three blades behind them. This is not an issue with any of the shavers but it's something to watch for with off-brand models.
The secret to getting a clean shave with a foil electric razor is making long, straight passes with the shaving head. Higher-end foil shavers come with a spring-loaded head, which flexes to help maintain just the right amount of pressure on each pass. In general, in my opinion foil shavers give the best shave of all electric shavers; however, they also tend to be relatively loud and can struggle to cut longer hairs.
Of course, neither foil nor rotary shavers can shave quite as close as manual razors -- but the best models get pretty close.
Don't make a snap decision.
Rotary shavers work better for men with dense hair and round faces, while foil shavers are better suited for men with light hair and thin faces. However, your personal preferences will always trump these broad generalities. It's also important to realize that it can take a few weeks for your face to adjust to any new shaver, so if you're not happy with a new razor right away, don't be too quick to give up on it -- you may see a major difference in results as your skin and beard adapt.