In my experience, Fords generally uses Bosch O2 sensors as OEM equipment. That said, I haven't changed my Contour O2 sensors yet.
Yes, I'd pay a little extra for the Bosch sensor. Note that sometimes Bosch sensors are sold as "generic", but generally it's only because you need to re-use the old sensor's connector (the new sensor comes only with plain wires). I've done this before without problem, but I've always soldered the new electrical connections (highly recommended). If your old sensor's connector isn't in good shape, don't take chances; find a high-quality sensor that comes with a new connector.
