Any of those can be good to great, though Last Extremity is the weakest... and it really depends on the roll, except for chaos dogma. I love the Dogma and it's one of my favorite scouts but there is a big portion of people who think it has too much kick and not worth the tradeoff. Keystone is one of the most balanced stat-wise across the board so if you have a good roll on that, give it a shot.
Grasp of Malok is one of the most accurate pulses in the game and very frustrating to play against. Totally worth leveling.
You're in for VoG in a half hour don't forget!
Though I am probably down to help with a WotM afterward depending on time