Information for choosing SAP Module?What is the best SAP Module for me?

Hi, i am krishna.   I completed my BTech and working as a mobile application developer (3+ years exp) and now i am doing MBA also simultaneously.

I want to change my career in to SAP domain,but i am confusing to choosing the SAP module.I researched some of the modules like SAP BI/BW,HR,MM,SD, CRM , FICO.I am confusing totally to selecting the module,which is the best module in the market and having the good scope in the future aspect and which is  the best module suitable for me?

I need the suggestion which suits to my career ,help me Guys...

Thanks

krishna