SRS.

SRS is fully capable of any map mod, any boss, has one of the highest DPS in the game, has next to no true gear requirement - 10% of rare helms you find late game have +2 minions. That's good 'nuff. It has a lot of versatility, and one of the cheapest starter setups. SRS even has good map clears that are very safe. At all points, SRS is a monster that's hardly touched by other builds.

Essence Drain / Contagion is capable of all content, and is much faster than CoC cyclone if you play it to be fast. The only thing it lags behind on at all is bosses, and even that isn't bad. It's certainly Uber Atziri capable.

Voltaxic lacks a bit on bosses, but completely demolishes all trash. For leveling builds, I honestly feel Voltaxic is one of the best - since 95+ you generally skip bosses or do lower tier maps anyways. It's certainly Uber Atziri capable, just not the build I'd use for her personally.

Low Life Spectral Throw is insanely expensive to pull off, but we're talking about 150ex - 250ex CoC Cyclone build here, so meh. Once you have the gear - LLST can clear everything at record times. Not much to say there - I honestly feel, even after nerfs, LLST is one of the most powerful builds in the game.

As for the disagreement: Just look at how fast each spec clears a pack. Watch how they clear them. Cyclone slows your character down. Period. Spectral Throw is an attack that can follow you for multiple packs. Once you get headhunters rolling, Spectral Throw can just fly through everything. Cyclone has to kill each pack, Spectral Throw lets their boomerangs do it for them. Voltraxic is shooting offscreen anyways, lots of things die just by chance. Flicker, with a good mob layout, can't really be touched in clear speed, as well.