Guild Wars 2

Initial Strike: Attacks with the first weapon-skill slot have a 7% chance to regain 1 initiative.
Opportunist: Critical hits have a 20% chance to restore one initiative (1-second cooldown).

Someone may want to double check my reasoning, but this is how I made my choice.

Initial Strike gives us a flat 7% chance to regain one initiative, so we need to know when Opportunist gives us the same chance per hit or better.

Opportunist = Initial Strike

To find Opportunist’s flat rate to give us back initiative on any hit we use:
(Crit Chance)(20%) = Opportunist

And we want Opportunist = Initial Strike
So
20% = .2
7% = .07

(Crit Chance)(.2) = .07 so divide each side by .2 to get…
Crit Chance = .35

Long Form:

(Crit Chance)(20/100) = (7/100)
Crit Chance = [(7/100)/(20/100)] = [700/2000] = 7/20 = 3.5/10 = .35

So Opportunist gives a 7% chance on any hit to give back one initiative when we have 35% crit chance. So if our crit chance is above 35% then Opportunist is the winner.

Opportunist also appears to work with any ability so think of all the time when you are not using the first weapon skill.

I like Opportunist if its a choice between the two.

Initial Strike is broken and doesn’t return any initiative, unless they ninja-fixed it, but last time I checked it was still broken.

So Opportunist all the way.