Hi Linganathan –
It depends where you are aiming at.
If you want to build on your expertise as an ABAP consultant I recommend taking the HA400 course. This course is exactly targeting your profile and familiarizes students in adopting and optimizing ABAP code for applications running on HANA as a database (e.g. ERP, CRM, etc.).
Recommending HA200 or HA300 is more a question of evolving into another profile, such as an technology consultant with special expertise on HANA (= HA200) or and implementation/application consultant that is e.g. building data models within HANA (= HA300).
Hope that helps.
Tim