I have all of the Zetas mentioned here. I currently believe with great mods I am running far and away a better strategy team. i am in a very reactive meta that has already swung in favor of R2 which is why I ditched Zaul.
I am running is Zader (L), nihilus, zoba, GK, and a very fast SA. It absolutely demolishes rex + r2 + (whatever else they run, and super demolish tthem if chaze is present). SA ensures you get off to a head start with zader dots, and nihilus ability cooldown goes first against rex. Against Zaul its a struggle, but still pretty easy to manage a victory since GK soaks up the opening wave. This combo gives you 3 unavoidable attacks (so who cares about Maul dodge), and is very tanky (except SA, but he is hidden most of the time). It also features 2 Aoe ability blocks (ability block from zader basic also). 2 dispels (boba,nihilus basic). It also features GK cleanse-retribution. Very balanced, very deadly, and now with SA very fast.
We currently have in our top 20.
9 rex+ r2 teams
8 maul teams (and dwindling since they cant really beat rex+r2)
3 Zader teams (mine is the only one running SA so far so beating the other two is super easy)