I'll just add that protection powers on an Adept (Barrier, Energy Drain, Reave) really need to be at high rank to make much difference, and also require a significant commitment of cool-downs to make them useful. This, in turn, requires adapting your play-style to their use. With Energy Drain, for example, rather than just stripping and warp bombing shielded or synthetic targets, you need to think about enemy shields and stripped mechs as a expendable resource, keeping track of when you last drained a target, which targets are left to drain, when you have available cool down, etc. It definitely adds a layer of complexity to how you approach an engagement.
In contrast, Stasis and Slam are useful right away at rank 1, fit nicely into the Adept's "base" toolset (filling-in weaknesses of Singularity or Pull without completely readjusting play style), and just add a bit of variety and flexibility. Stasis, in particular, is simply monstrous when paired with Singularity on an Adept. Some on this forum have argued it should have been native on Adept in the first place.
Warp ammo is hugely popular on Adepts, but I honestly don't think it adds much on Insanity. Unlike Cryo, Incendiary, or Disruptor, Warp Ammo only adds damage, and this additional damage is only really noticeable at high rank and early game (when it requires the most commitment of other resources to have at high rank…). If using an ammo power, my advice would be to take Jacob, Grunt, or Zaeed (depending on mission) sporting a squad-evolved immobilizing ammo.