To be honest, the Indian government's e-filing site is good enough for a vast majority of tax payers. The interface is simple and fast. If you have a digital signature there is no need to mail any hard copies of any documents.
Meanwhile, ClearTax is really helpful if your returns are complicated. You have 3 houses, own stocks and a business etc. If you sign up for their gold package, a dedicated CA will assist you in all your returns and is available throughout the year over phone or email.