Mob Scene
A lot of thought goes into the idea of the “balanced” party. The fighter (tank), the cleric (healer/ buffer), the wizard (controller), and the rogue (striker/blaster). Which is one way to look at the party, skipping the subroles of face, trapspringer, AoE blaster, etc. But the balanced party isn’t the only way to play, and it’s possible to double up on roles. Which can be fairly effective: the all damage per round party will not have much in the way of healing or crowd control, but might kill things faster than the party can take damage, negating the need for the leader character.
I usually consider the environment to be important, too. In a dungeon, the usual party will be ok; in woodland, however, a ranger and a druid will fare far better than a fighter and a cleric. With a ranger in the group the need for a thief lessens, so it will leave space for another character (a bard? a barbarian?). Also, why only 4 characters? I consider the best group to be the one with 5 elements. The progress in experience may be a little slower, but the increase in survivability balances this.
A theatre of rogues, of course.
“With catlike tread, upon our prey we steal…”~♪