What display profile should I be using to edit photos in Photoshop RBG?

The best profile to use is the one that most closely matches the characteristics of your display. Apple ships generic profiles like "Color LCD" that represent the average of the displays coming off the assembly line. Some profiles, like "Adobe RGB" or "sRGB" are intended for use as working color spaces in Photoshop and other photo editors and must not be assigned as a Display profile because they don't match the spectral/tonal response of your monitor. Stick with Color LCD, or make a profile specific to your monitor by using a calibration device such as a Huey or Eye-One to objectively calibrate your monitor. You can try the Calibrate button in the Displays dialog box, but the problem is that human eye calibration is notoriously inaccurate because your eye automatically compensates for color casts.

For similar reasons, how it looks is not very relevant. It may have no bearing on how accurate the grays and colors are, colorimetrically speaking.