I have all 3 but my opinion will be diffent, i run suicides mastery.Domino she is very randomly.I will choice Emma Frost over Havok for some reasons1) Suicide friendly 2) A lot of immunities3) Damage and crit chance rate grows with prowess stacks, there is a high chance that the second special crit ( my 6* rank 2 with suicides = 70k-80k damage from sp 2 with very high crit chance.4) Very easy to ramp up / play / gameplay 5) Very tanky6) Bypasses evade champions7) Power control - ability control ( concussion ), power stingWhat I do not like about havok, he has no immunity to poison or to the bleed to play with suicides. + Reduced power rate + very long ramp up if unduped + depends on parries and heavy attacks what is problematic againts limber / stun immune nodes. No evade / ability control.Pros are that non-contact hits and high damage over time debuff + very strong sp 3.I often play as Emma but take havok against korg, electro. If Emma Frost had non contact medium hits, i would take her any day but she doesn't have them, so in such moments I take a havok instead of her