Also AMS doesn't kill you, you can tank through AMS, also AMS gives you an immunity so it can't be constant. Chaining AMS also requires usually vocal communication on the teams part or atleast a designated firing rotation order. Oh yeah AMS also has a cooldown.
Leech can lead directly to your death from a leech team, its hard to do much of anything with 24+ stacks of leech on you while the people shooting you all just got +20 or so to there power levels.
It has no cooldown, no immunity, and costs almost half as much CP.
You get bonus points to your leech team if you use energy siphon, lolarons, and siphon drones.
Yeah, but it doesn't have sparkles being shat out of your ship everywhere.