Ok, Im gonna start this out by saying I know little about rocket engines, but I sure wish I knew more. When looking at things like specific impulse, thrust to weight ratio, actual exhaust velocity, etc; what type of rockets are the best choice/most used? Ie, solid, liquid bipropellant, hybrid, tripropellant? How would an air-augmented rocket compare to these in specific impulse, thrust to weight, and actual and effective velcity? I LOX/LH2 probably has highest specific impulse, or atleast the highest Isp thats stable or economically practical? Thanks for any help.