I want to know best/secure way to pass dataset from one aspx page to another aspx page.

Besides using Session or Query string or ViewState to hold you dataset to pass to other page, you could think of using Cache object. Read more on this at this link and here.
One more option is use 
Also, read on options of state management that are described in this article: ASP.NET: Nine Options for Managing Persistent User State in Your ASP.NET Application

best and secure way to pass dataset from one aspx page to another aspx page is Session.
u can store DataSet in session variable on first page
Session["DS"] = objDs;
and then u can redirect to another page and access that dataset on other page as follows
DataSet objDS;
objDS = Session["DS"];