Right, Bolt Caster IS vastly superior single target, it's more that although I could pull singles plenty while levelling, I was much more commonly fighting 2-5 mobs, where the electrocute build is stronger. I would sometimes see them conveniently located and just hit all my buttons and pull up to like 12 mobs with that nonsense. Worked great. Personal preference (in a raid or dungeon you'll swap based on fight, amps are the same thankfully).
For tanking there are TONS of viable builds. Since I'm still undergeared in that regard I've been trying to go as survivability oriented as possible, I don't have repair bot and it still bugs out medics as far as I know, which is what I'm playing with mostly, so I'm just sitting on points waiting for the boosted armor amp to finally exist. I run Shock Pulse, Particle Ejector, Disruptive Module as my attacks, then just hyperwave, bruiser bot, recursive matrix, Personal Defense Field and Zap. Nothing really fancy or super complicated about the build, just what I've been doing.