Which is better Nintex or Conga composer for generating of documents and why?

Hi Kapil,

Nintex Document Generation (formerly Drawloop) lets you tap into content from Salesforce data, Apex or external sources. Use predefined templates to generate high impact document packages using any combination of Word, Excel, PowerPoint, PDF or Visualforce pages. Route generated documents to virtually anywhere via email, e-Signature or Nintex Workflow.

Conga Composer lets you create templates & produce consistent, on-brand documents automatically in one click, using ANY standard or custom Salesforce object. Eliminate time-consuming, error-prone manual tasks. You can scale up to produce 1,000s of documents a day without more staff.

WebMerge automates your document creation so you can get back to business. Automatically merge Salesforce object data into a PDF, Word document, Excel spreadsheet, or PowerPoint presentation in an instant. Never copy and paste again!

And there are alot more apps on appexchange that performs document generation task with different customizations, So it upto you or your business logic which app you want to use. Because there are many factors that changes you app selection {Like App Pricing,etc}

Hope this helps you.