Rav Abraham Azulai (grandfather of the Hida, 1570-1643), in his Hesed Le’Abraham (chapter 55), lists the order of preference of materials from which the Menorah should be made. Starting from the most preferable, his list is: gold, silver, bronze, copper, iron, tin, lead, glass, wood, bone, glazed porcelain, unglazed porcelain, pomegranate shell, coconut shell, acorn shell.
Many silver Menorahs are used with glass oil cups. Rav Shlomo Zalman Auerbach (Jerusalem, 1910-1995) ruled that since this is the normal way of using a silver Menorah, those who use such a Menorah are given credit for using a silver Menorah – which is, of course, preferable to a glass Menorah – even though the candles are in glass cups. The glass cups are considered part of the silver Menorah, and thus using such a Menorah counts as using a silver Menorah.
Today, pre-prepared oil Menorahs are available, with the oil and wicks already prearranged. The companies who produce these kits add coagulating agents to the oil to make it solid, and after the candles are lit, the heat causes the oil to return to its original liquid state. Rav Yosef Shalom Elyashiv (Israel, 1910-2012) ruled that since the coagulant constitutes less than one-sixtieth of the oil, it does not affect the status of the oil with respect to Hanukah candle lighting. Therefore, one who uses such oil is considered to have used olive oil for the lighting. Interestingly, Rabbi Bitan, in Yalkut Yosef (p. 118), cites the work Teshuba Me’ahaba (Rav Elazar Fleckeles, 1754-1826) as asserting that the oil used in the time of the Hashmonaim was solidified oil. If this is the case, then coagulated olive oil would certainly be acceptable for use, as it resembles the oils used by the Hashmonaim when they kindled the Menorah.
Summary: The order of preference for the material of the Menorah used on Hanukah is, starting from most preferred: gold, silver, bronze, copper, iron, tin, lead, glass, wood, bone. One who lights a gold or silver Menorah with glass oil cups is credited with using a gold or silver Menorah, even though the candles are lit in glass cups. Pre-prepared Menorahs with olive oil that has been coagulated may be used for the Hanukah candle lighting.