Rockets is pretty useless for anyone except Germany and Russia.
Jet Fighters is nice for Japan and America, who generally have at least a few carriers. The boost to fleet defense can be worth it.
Super-Subs is generally nice for Japan and America as well…the only other country likely to mass enough subs for it to be worthwhile is Germany, and if your doing well enough to be building lots of subs as Germany, you probably don’t need the tech.
I highly recommend Long-Range Aircraft for any nation with the cash to spare on tech-rolls, especially for America and Germany. It makes defending Germany from Allied invasion much easier, and aids greatly in America’s efforts in the Pacific (especially when coupled with the “Island Bases” National Advantage)
Combined Bombardment is generally useless, but Japan has a couple National Advantages that might make it worthwhile.
Heavy Bombers are generally not worth the double investment (dice for tech AND bombers), but if your going by the book rules, they can be quite powerful against enemy fleets when used in combination with your own fleet.