Although I do really like the bubbline [bubbler whatever] for the fact it can make a shield and has very good range. It's not useful against bosses, and if you do get hit, it's reduced to nothing.
Of course I do love the Spur, and consider it the best weapon. It's very useful even just to have it out, because it does not get a reduce in levels from getting hit. It's also very very powerful and once I get it, I really only use that, unless I see another opportunity where the other guns would be better.
The fireball is also very good, I usually just run with the balls so the things I shoot, hopefully get killed before they hit me.
I only ever use the missile launcher for the hell bosses.
Blade is also very powerful and I use it a ton too. But with the Spur's extra range I prefer the Spur.
I never use the snake for some reason.
If I'm not doing a hell run its the Machine Gun, which I do like a lot. And is actually quite powerful.