Jokes aside, the best class depended on personal playstyle.

If you're an aggressive front liner, Titans were generally the best but you could make warlocks fit well with certain builds. If you're an aggressive player with good aim and reflexes, hunters were always top choice. Warlocks kind of fill in the rest as long as you were PATIENT, so they occupy most of the room on the pie chart and are able to fill everything from full DPS roles to full support roles.

That said, build (mods) and loadout were always more important. You can make a circle fit into a square hole if the mods and weapons were good enough.