You've got other options, just in case you haven't considered them.
Chill (Shadow Spells page 16); direct spell (so the target doesn't get to dodge) that deals Stun damage, and has a chance to lower initiative (1 per net hit, max 5)
Firewater (Street Grimoire page 103); combines fire and water elements, so has chance to light a target on fire and cause knockdown, Also, the area around the target equal to (Force/2) in meters becomes slippery, meaning all actions involving movement, which includes defense tests, take a -2 dice pool modifier.
Ice Spear (Street Grimoire page 103); does Cold damage and can permanently break armor
Lightning is a pretty common choice, and as Top Dog mentions that means several opponents may come prepared. Several mooks in adventure modules have non-conductivity upgrades, so that's something to consider at least.