Will you please tell me that amongst CA/ICWA/CS which course is better ?

All the CA/ICWA/CS three courses have similarities with regard to the course syllabus

The only difference being the subjects studied and the examination orientation.

Chartered accountancy course has in depth study deals with financial accounting, auditing, tax aspects.

Cost accounting course has in depth study deals with cost and management accounting.

Company secretaryship has in depth study deals with company law.

Scope after ICWAI:
You can work as following posts given below:
Accountant
Auditor
Certification of manufacturing account
Certification under export & import policy
Chief Internal Auditor
Consultancy assignments
Cost controller
Finance manager
Financial controller
Excise Audit
Finance Director
manadatory cost audit
Managing director

Scope after CS:
You can find jobs in following areas given below:
Airport Authority of India
Oil and Natural Gas Corporation Limited (ONGC)
Government Financial Institutions
Stock Exchanges
Accounts Branch of the Central Government Law Services
Bureau of Public Enterprises
Bharat Earth Movers Limited (BEML)
Neyveli Lignite Corporation Limited
State Infrastructure Development Corporation Limited