Control is one of the only player-versus-player (PVP) environments where Defender makes sense. With the Defender’s super ability, you can lay down a bubble that’s literally the same diameter as the objective -- and with two armor buffs to choose from, you can either fight inside or outside your territory to take the objective.
Plus, the duration is long enough to both neutralize and capture the objective all at once. Sure, there are some strong shotgun or melee choices your opponent could make to put you down, but you should equip yourself with the same resources. You also share your bubble buffs with your allies.
Obviously, you may not end up with the most points on your team, but you’ll consistently find that the team with the Defender wins the most often, and that’s more important than individual score.
The real issues are the Nightstalker and Striker super abilities. If you see that the other team has a Nightstalker, either charge your super before he can, or wait until he blows his big purple arrows on someone else. The Nightstalker super turns off your Defender bubble, leaving you naked with a wasted super. Hopefully you weren’t taunting inside your bubble when he cracked you open.
The Striker super is a little easier to counter, as he has to get all the way inside your bubble to effectively kill you and turn your power off. Beware though: he can wipe your whole team if they’re counting on your protection on the control point.
Plus, the Striker and Nightstalker are great even if they’re not countering a Defender. If the enemy team groups up on a point, both subclasses are made to punish them for their proximity.