Pros and cons: materials for load-bearing columns

I'm having my front porch rebuilt, including new columns. The current ones are wooden, round and tapered (maybe 8" or 10"). Because our house is sort of Arts and Crafts style, we think we want to go with box columns. The porch bears the load of our second-floor dormer. What are the pros and cons of the various materials used for columns? Each contractor seems to have different ideas about the various materials (steel, fiberglass, wood, aluminum, etc.). Thanks!
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