Which cross class abilities should i get for Machinist?

[Zophar]

Feint because someone's gotta use it and keen flurry so you can pull whenever you want and have a "defensive cooldown" to pop while the tank pulls aggro back from you.

Or, you can use Keen Flurry in, say, final coil, when you have a Phoenix Pinion charging at you, or during Bahamut's Earth Shaker. You know, just to help your healer out a little?