scout :
regular scattergun is really good, experts scout use it often tbh
your pistol is good to finish off fleeing enemies
your bat is sometimes useless sometimes not, but its really good to finish off enemy after shooting 2 scattergun meatshot to an enemy
soldier :
stock rocket launcher is the best at every situation, but black box are good to if your team is really bad or dont have any medics
buff banned or concheror is the best for supports and buffing your team, batallions backup is very situational
use the shotguns if you want to play more offensively, but you will most likely die more often
for melee use the escape plan, its the best overall, dont use equalizer or market gardner, its sucks
pyro :
the degreaser or stock flamethrower
scorch shot if you WANT TO BE THE MOST HATED PERSON IN THE SERVER or regular flare gun is good, don't use the shotguns
for melee, i all of them are good and pretty balanced, so its up to you