The only Doom 1/2 Weapon which I do not like is... BFG9000. IMO, you don't use it for low-level enemies, since it's a waste, and when used against the CD/SM, it still needs to pump a few shots off, to actually kill them.
IMO, first time I played Doom 1 and got to Dis, I kept my BFG ready for the final boss. So I run out, right into the SM, fire BFG a few times and... the end screen appears, as I kill the Mastermind. To this day, one of the most anti-climatic bosses in a game which I got through.
The bfg's most useful property is simply crowd control really. Especially in situations where there's a lot of minor enemies with something like an archvile mixed in since the priority is taking care of the archvile so it can't easily attack you or revive all the dead enemies.