I operate the OSX System, have used Lightroom since it first started, currently use Lightroom 4, waiting for LR5 (Beta now out)
Lightroom: for filing all my Photos, basic changes such as White Balance Adjustment (I shoot RAW), any cropping needed. Only drawback no Layers.
Photoshop CS6: After LR4 adjustments, I move to CS6 for any thing I plan to do that requires Layers adjustments.
On One: Now do about 70% with this software that I once used Photoshop for, more intuitive & much easier to use than Photoshop, very good "Brush" technology, but doesn't do everything Photoshop does.
NIK Viveza 2: Use this for very localised adjustments, but less so now with the advent of On One.
NIK's Silver Effex pro 2: Best B&W software available.