Well both classes have pros and cons. Well geared Punishers are capable of dealing huge amounts of damage and can kill in about 2-3 hits if they get their stun off before the target makes a move (If target is melee) or if they far enough within their range (Applies for both melee and ranged) and if the target has average gear (In my experience at least). Well geared Sentinels can also do that, stunning the target if melee and if they are far enough but within range, but in my experience sentinels need to use 3-5 skills to kill me if they get their disables off. In my experience, Sentinels with very high EVA are very difficult to kill. I have no problem with Punishers as long as I can disable them before they get their stun off. Sentinels are also very fast and tend to deal huge damage when in mech mode (Except Kuune, he's a monster), while Punishers deal huge damage even if they are not in mech mode but a slower pace than the Sentinels. All the things I've said here are from my experience it will most likely be different for everyone.