Articleship

Variety of work

Taxation - DT, IDT

Audit - Statutory, Internal, Concurrent

Consultancy

Etc

Adding to what Sashikant has already said,

1) The attitude of the firm with articles

2) The work conditions

3) Size of the firm - No of partners, staff etc

4) Major audits - Banks, PSUs, C&AG audits. etc

5) Stipend offered 

Adding to above info, the qualification it is expecting from its article students,the leaves it is granting for your final preparation,Past expereince of the firm etc etc........