In my opinion, different weapons are supposed to be different playstyles, so it is completely fine to prefer a certain weapon, but also consider analyzing the other weapons and what upgrades are best for them, for example, the flame cannon doesn't need bullet damage so you can take upgrades that sacrifice bullet damage for massive boosts (e.g. double shot), and splinter makes the whole horde into a very accurate metaphor for a nuclear bomb, and if you take the pyro mage path all the way, you will heal occasionally when you burn them (you'll be burning them a whole heck of a lot).