The Shulhan Aruch (O.H. 671:7), based on the Gemara (Shabbat 21a), rules that it is a Mitzvah to place the Hanukkah candles to the left of one’s entrance-way. In such a way, the Mezuza is on the right side of the door, the Menora is on the left and therefore when one lights, one is surrounded by Mitzvot.
Rabbi Avraham Azoulay (gloss to Levush § 671) comments that in most years, Parashat Miketz is read during Hanukkah and that the word in the first verse “Shenatayim,” stands for “Semol Ner Tadlik Yemin Mezuza” (lit. “On the left light the candle, and to the right is the Mezuza”). Similarly, his great-grandson, the HIDA (Midbar Kedemot, Ma’arechet 8), writes that the word “Yamim”, which is also in the first verse of Miketz, alludes to “Yenichena Mitzad Yemin Hayotze” (lit. “One should place it (the Menora) to the right of one who is exiting [that is, opposite the Mezuza]”). Furthermore, the Kaf HaHaim (K.H., O.H. 671:58), quoting the Sheiltot DeRav Ahai, says that when one lights the Menora to the left of the Mezuza while donning a Tzitzit, one fulfils the verse (Kohelet 4:12), which says that a three-stranded cord is not easily broken. In this case, each Mitzvah represents one strand and together, they have great spiritual benefit.
Nowadays, it is challenging to fulfill the Mitzvah of placing the Menora to the left of the entrance-way. For one thing, the main objective of placing the Menora at the entrance is for passersby to see it, which publicizes the miracle of Hanukkah. Since most home doors these days are not made of transparent glass, it would not accomplish this objective. As well, if one were to simply leave the door open, it would expose the Menora to wind, rain or snow, which could extinguish it. Therefore, if one cannot place the Menora at the entrance, one should place it near a window which faces the public domain so as to fulfill the Mitzvah of publicizing the miracle.
Summary: The ideal way to fulfill the Mitzvah of the Hanukkah candles is to place the Menora to the left of the entrance’s Mezuza and that the candles will be visible to passersby outside. If this is not possible, one should place the Menora by a window which faces the public domain.