I have been recently introduced to SAP and its SCM applications. I am a young logistician trying to get a foothold in the supply chain management world. I happen to like all the parts of SCM that SAP has to offer and I which SAP SCM application is the most marketable?
SCM is one of the strangest areas of SAP. The reason? Supply chain management continues to be an important area of concern for SAP customers, but the flagship SCM product, APO, is not doing very well as a consulting area because most companies are avoiding complex and time-consuming APO implementations. For that reason, a good deal of what SAP pushes as "SCM" is more connected to the core logistics functionality that you have always been able to find in SD, MM, and PP. That's why I suggest that those who are interested in SAP SCM get a solid grounding in SAP Logistics. This is a good time to do that, given the amount of SAP customers that are upgrading to ECC 6.0. Many of them will need consulting help in the core logistics components. As you build up that Logistics background, what you may find is that the market for the SCM side of things heats up.
SAP is working hard to make the supply chain components quicker to implement with a higher return on investment. So you might be able to add to that core Logistics exposure by implementing more cutting edge projects such as RFID, or perhaps even working with some related xApps. So get your grounding in the functional core, and then look for opportunities to dig further into SCM. Finally, remember that the best SCM consultants of the future will have some degree of industry specialization and will also have deep overall knowledge of "best business practices" in that area. Another way of looking at it is to say that it's just as important to become an SCM business process expert as it is to learn how to configure SCM products.