A. Find out the cost of making cans and bottles.
B. Find the environmental cost of each.
Mining, smelting, and forming aluminum. It is mined in third world countries, smelting requires huge electrical input, and is formed in another part of the world requiring huge transportation costs.
Glass is made from basically sand, but does require significant power input, then transportation.
I don't know what is easier and more environmentally cheaper to make.
C. Look at recycling. Neither breaks down naturally in a reasonable amount of time.
Aluminum is easy to reycle, but does require smelting. It is much lower cost than making new ones. It should be easy to find those costs to compare.
Glass is also easy to recycle, just melt it and reform it, but with impurities, glass tends to go to green or brown. Consumer preference seems to be for clear which is harder to do. One problem with glass is that the raw materials are so cheap, that there is not a huge savings in recycled glass cost.
But if you start here, you should be done in no time.