Uttarkhand is full of abundant nature, that it is called as trekking paradise in India. Right from Chandak hills trek to deoria tal trek, right from Hemkund sahib trek to mandani valley there is lots to view. Himachal Pradesh trek shows more of the Himalayas, snow, snow peaks and glaciers. Bhrigu lake trek Hampta pass trek chandrrkhani trek or be friendship peak trek, if you want to view lot of snow it’s an ideal spot. My suggestion would be Uttarkhand which has all under one roof to trek. Though someday you should trek in Himachal too.