Nippon Denso has been a big parts contract holder for years, I don't know if they still are though.

Denso parts are found under the hood of most Japanese imports, Hondas, Mitsus, Mazdas, etc. They are a good company that makes good parts.

An OEM Denso O2 sensor is going to be a better choice then a Bosch sensor, but will cost a lot more.