Aluminium is tubing and it can get dented or bent. CF will not bend much but will break. Steel will also bend if it is tubing. Solid steel will be extremely heavy.
In the end you need to ask yourself what abuse you will be putting the tripod through. You also need to ask yourself if you are going to travel with it, if you are going to check it in, how you are going to pack it, if you are going to be carrying it all the way, etc. How you are going to use your tripod will determine what you can live with also. How you pack your tripod will also matter.
Everything will break with enough force applied.
For some people, myself included, I have two different tripod setups. One light one heavier. I will use my lighter one for travel.
Don't forget that your entire support is only as strong as the weakest link. So if you get a super strong tripod but skimp on the head, the weakest link will still give you trouble.