You can't get them anymore, but when I was about 10 years old, the holy grail of firecrackers was the M-80.
Sure, there was the workhorse Black Cat - string firecrackers which came with the fun of teasing apart the strand to make "mini bombs". I'll never forget the incredible pyrotechnic potlatch of my veterinarian older cousin one summer down in New Orleans. He was a racehorse surgeon and totally loaded as a result. He bought roll after roll of black cats, the kind with hundreds of individual reports. We must have set them off all afternoon. I'd never encountered that kind of conspicuous consumption before. It reminded me a Mad Minute I saw in ROTC some years later.
There was the long arm of the bottle rocket, which in later years allowed for the Bottle Rocket Fight. You could build a bazooka out of PVC, work up some crude sights out of an old ruler, and drop a bottle rocket into somebody's hip pocket from about 60 feet away.
Cherry Bombs were good, potent, but nothing like the M-80. I had always been told, even by my father, that tthe M-80 had the equivalent explosive force of "about a fifth a stick of dynamite." In college, reminiscing on the m-80's passing, others cited this metric of explosive power with a cast-iron certainty, which makes me think it's either true, or one of those memes that spread through the strength of some legitimate sounding number. That "1/5th" value seems so off the wall that it must be true. In any case, I really do think they were used for some commercial blasting applications, but what I know with a cast-iron certainty is that the old m-80 was hands down the most powerful firecracker out there.
It would blow a beer can into glittering chaff-like shrapnel. You could stick the unit into the can, light the fuse, then toss it in the air. WHAM. The pinwheeling aluminum would shower down around you. You could tape a rock onto it, and toss it in a pond. That the unit worked off the power of rapidly expanding gas was evident the in the enormous bubble you could watch form beneath the surface. You could drop one lit into an open ended piece of steel pipe, chase it with a handful of gravel, and presto - instant cannon with grapeshot! We shot holes in plywood scrap, milk jugs, you name it.
Of course, people were blowing their hands off with them, apparently. They got taken off the market. Looking back, it was funny how precise my brothers and I were about using them - clearing the range, announcing ignition by yelling "Fire in the hole!". Our engineer father had actually walked us through it, the safety procedure, why things were done that way. I guess that's why we never got hurt.
They sell a thing now that's an "M-80" brand firework. It sucks. It looks like the familiar red cardboard tube and side-tapped safety fuse, but it's really just an anemic cherry bomb. For true firework power these days, you'll need to roll your own.