Which is the better strategy to follow at any point of sales software application company? Direct sales or through channel partner or both?

It really depends on what your business objectives are and your target market.

I would consider a channel mode if our target audience are small retailers and have a huge market to cover (like in India). Having a local presence in each area to selling and support your customers would help you address the reach.

If your target audience are big retailers and business groups, then a direct sales approach would suffice.