One way to determine who's better is to count the point values of the pieces. White is slightly ahead by 1pt, if you add the totals of the point values of each side. Another way is to determine mobility of the pieces. It seems that white's pieces are more mobile than black's. A third way is to see who's king is safer and if the other side can possibly amass an assault on the king. I think black would have a more difficult time attacking, therefore black should be more on the defensive. All in all white's winning this position.
Is it the fact that you have a bishop vs rook situation? The bishop is more mobile than the rook; plus, your bishop cotrols the all important a1-h8 diagonal. This should provide you with chances to win.
Seriously read the 2nd post! geez...