This is my first post here, so I hope I don't step on my tail...

Personally, I don't think any specific color really matters. Some folks prefer to have a civilian looking pack mainly for the reason, if applicable, they do not want to look like LEO or military. Depending upon the situation, that kind of attention could be less than desirable.

I would concentrate on the kind of equipment you plan on carrying, how you may wish to organize it, and make sure the pack you get can withstand anything and everything you throw at it.

Personally, I use a khaki Eagle AIII MOLLE pack, for both my assault pack (when I'm in the field) and as my BOB. It can be found here

Are there any specific options or features you prefer on your pack?