I still think spur is the greatest because it wields the same amount of power despite energy crystals. And it's both effective against normal enemies (as polar star lvl3) or against bosses (charge attack). And unlimited ammo!
Blade's cool, just for the fact that it's king, and King is awesome.
Machine gun if fun to mess around with, but between the easy level down and the weakness at level 1, it lacks power.
Fireball's range is pathetic. The shots are slow, and have problems with gravity. Although it's great for cheap shots on bosses, if you have a high place.
Snake is powerful, but has a tendency to level down, which makes it useless during the first few minutes of Hell.
Nemesis + Crystal = Duck. Duck = Pathetic
Polar star is fun, but gets annoyingly weak.
Bubbler is fun, but a pain to level up.
Rockets & Super rockets are great to use once, but you just can't depend on them. Unless you have infinite. Which is why I love Crowned Witch so much.