If showering, disposable cartridge razor. Tried a double-edged mechanical flip-top razor, not comfortable with it safety-wise. Hard to handle, despite knurled handle, with soapy hands and no mirror in the shower.
I occasionally use one of those $10 Harbor Freight electric razors if in a hurry. When I was working, I kept one in the car for commute and going-to-offsite-meeting shaves. When battery went down, I'd switch it with the one in the house and recharge it.
I've had Remington, Norelco, and various el-cheapo (like the Harbor Freight ones) electric razors and the absolute best so far is my Braun Series 3.
Smooth shave, recharges very quickly (has a charge indicator light on it), is washable, easy to handle.
I especially like the charge indicator because I suspect it has two cells in it, and it glows red when the charge is getting low. This avoids the reverse-charging on the weak cell if you keep using it when only one cell is running the works. Had it for about five years now, use it very extensively, and I think the charge capacity is finally degrading. Seems to recharge especially fast if you run it down to where the red light lights. Impossible to over-charge it because of the regulator, which contributes to the batteries' longevity.
Like most electrics, a greater number of passes over an area is required if my beard is neglected for a day. (However, since it's now grey, it doesn't show as much as in my yout'.)
Foils and cutters are expensive ($30-$35 a pop), but in terms of amortization, are pretty cheap even compared with disposable cartridges, which started to hit $22 a pack. I keep a new spare set handy for when they wear out... holes start appearing in the foil.
I found it pays to keep it clean and lubricated. Braun's shaver oil is expensive, so I just dab sewing machine oil on the working parts and that almost seems to be better than their proprietary oil.
Terry
Incidentally, I might have voted three times... I kept getting thrown out by a "This Page Can't Be Displayed" message.