Remember, for something to be visible it has to either shoot out X amount of light or be of a certain size or a combination of the two. Tape is going to generally be covering only a small part of the bike unless, of course, you wrap a bunch of it on your posterior giving a whole new meaning to getting "mooned"
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I would think that reflectors would be better.
But the problem with reflectors and tape is they are both passive. That is they have to get struck by a vehicle's headlights and that reflection is what the drivers see. So the car has to be pretty close for them to come into play.
There are plenty of rear blinkies that have a visible range of about greater then .5 mile. I am a strong believer in using one or better yet two of these when I ride. The sooner they see me the better.
Even so, there are some areas I will not ride. Last year, a cyclist was struck and killed on 441 rather near where I live and late at night. Late at night, people drive at high speeds on that road like 70 mph +. At that speed even a .5 mile cushion is only about 25 seconds warning. If the driver is fooling with the radio well then the warning is much less.