>steelDurable, lasts a lifetime, endurance threshhold (it can be bent to a certain extent infinity times and not break), easily repairable, comfortable to ride, cheap, heavy, rusts
>aluStiff, uncomfortable compared to other materials, good for racing, cheap, light, no endurance threshhold (even bending it very minorly will weaken it permanently), repairing damaged alu is not cost effective, does not rust
>magnesiumlol no one uses it
>carbonExpensive, very light, comfortable, stiff, good for racing, repairable but expensive to repair (a few hundred dollars for minor damage), no endurance threshhold (even minor bending will permanently weaken it), may or may not last a lifetime, no real use outside of racing, can be shaped in more aerodynamic ways than metal tubing, makes people think you are cool, makes people think you are a fred, makes people want to steal your bicycle, does not rust
>titaniumBest in every way except more expensive than everything else, comfortable, strong, endurance threshhold (can be bent a little bit infinity times and not break), repairable but expensive to repair, good to race, good to ride, makes people think you are awesome, makes people want to steal your bike, like steel but lighter and does not rust, stiffer than steel but not super stiff making it comfortable and responsive, hard to weld/repair which is why it is expensive, the one non-money downside is that it won't be as aero as some carbon tubing, best material for pretty much everything (except commuters because it appeals to thieves, and aero bikes because carbon can be more aero, and third world touring because steel is easier to repair), the kind of bike that God would ride if God was real *tips fedora*
http://www.ibiscycles.com/support/technical_articles/metallurgy_for_cyclists/ 
