It really depends on what you have in mind as far as "do-all". If a rifle is intended for sport and/or defensive shooting then I'm a big fan of the 1x4 optics like the Burris MTAC, Leupold Mark AR, or Vortex Viper PST. Those style of optics give you the wide field of view you'd want at close distances associated with personal defense or most competitive and sport shooting, yet they still offer enough magnification to reach out to the effective ranges of the rifle. So for a "do-all" optic that's really what I'd prefer. YMMV...
