What stat is the best for you depends of your current gear and your playing style . If you want to find perfect solution for you i can recommend you great web site for restoration druids resto4life I hope this will help you .
spirit has been significantly reduced as a primary stat for resto druids. many resto druids, such as myself, are now dropping all spirit and mp5 enchants/gems for spell power, int, and crit. Granted, I still carry two spirit trinkets (kologarn 10 and sarth 10) for long duration healing intensive fights (mimiron 25 etc.). Spirit remains my highest stat by default primarily because of the 15% spirit from talents.