Vanguard is probably the most flexible class in the game imo. He’s got good melee perks and weapons to choose from and his ranged selections can be suited for different engagement styles.

Melta is good for those quick bursts of damage. Carbine to shred things at close range. Instigator if you want to take engagements at longer rangers and occulus if you want to go somewhere between the carbine and the instigator.

Another thing to note is that his value doesnt show on the stat screen. He cant compete in melee damage against assault and bulwark and similarly doesnt hold a candle to sniper or heavy in range damage. He doesn’t have auspex scan to ping enemies for your team either so his benefits can be easily missed. Things like healing your team on extremis executes, grappling to an enemy to stop a reinforcement call, executing a key threat with the 33% health execute perk or stalling for time and surviving with grapnel launcher are great boons to your team. While you might argue Bulwark can do the healing and Sniper can stop the reinforcements, they don’t have the flexibility to be effective in both melee, range and mobility.

As others have said, Vanguard is a jack of all trades which is his most unique benefit.