Well they are two very different armies as far as gaming style goes.
Dwarfs are stable, solid, pretty defensive and in my humble opinion really very boring after a rather short amount of time (my gaming style is much more about getting at the enemy you see) but for a beginner they are probably an easy army to get the hang of.
Orcs & Goblins are wild, unpredictable, have a huge amount of varied units, the army can be what you want it to be really. Make it Orc heavy with plenty of tough stuff and you can be more defensive, or pack in spider riders, wolf riders and boar boys for mobility. It\'s a little less easy to construct solid strategies with them though because they really are pretty wild.
If you have a friend who is also getting Skull Pass perhaps find out what he wants and take the other army. That way you can trade and double the size of your force.
Or just use Skull Pass and the models to learn the game, decide what works for you and then get whatever army you think will fit your style. It doesn\'t have to be one of the ones in the box.
You could pop into a GW store if you have one close, try out both forces in some intro games, and make a decision from a slightly more informed viewpoint.
If you do this bear in mind that staff members tend to twist or completely ignore rules to speed things up and make the game more entertaining, so you won\'t exactly get a full view of what\'s going on, but you\'ll get an idea.
Oh, and if you are already painting I would put the paint set money towards something else. You don\'t need the little pots of off colour unusual paints you get in it unless you are a complete painting newbie. Even then I\'d say you are better off buying a few basic seperate paints that are more suited to what you are going to paint.