The Scarab God is the best of those three, imo. At 360 I think I'd run TSG, Strix, and Tezzeret. If you don't support the artifact deck, then Tezz could be swapped for either of the other two (or even Psychatog) depending on personal preference.
Wave if you're trying to support aggro. Wreckage if you're trying to support control. Wave if you want a card that might see play in a variety of archetypes. I'd go with Wave unless you feel Wx Control needs a boost.
What’s the state of the art on the black 5-drops ranking?
Shriekmaw is first i guess, but i’m not sure about the others (Doom Whisperer, God-Eternal Bontu, Custodi Lich, or even walkers like Amonkhet Liliana and Ob-Nixilis) but none of these hit me as a staple. What’s your opinion?