Transparent bottles are better because I can see the color of the olive oil.
Be aware that color is NOT a quality characteristic of the extra Virgin olive oil! This is why judges in international olive oil competitions use blue or red non-transparent jars when they smell and taste olive oil so that they are not prejudiced about the quality of the olive oil they are tasting. The only quality characteristics provided by the International Olive Oil Council are: Fruitiness, Bitterness and Spiciness. However, there is a more important reason why olive oil is placed in dark bottles. Olive oil must be protected from the UV rays of the sun that can harm its quality and create premature aging! This is why the Minoans (the first ancient Greek civilization) that started cultivating olive oil 4,500 years ago in Crete, used to store olive oil away from light and heat in storage spaces under the ground. Even the light from the supermarket lamps or from our home can create the same premature aging effect. This is why in Gaea we are using dark green bottles and for the Gaea Fresh and Gaea Planet we have painted the bottle so that no light can get into the olive oil and degrade it!