Do the certification in a module that has relevancy to your work profile like
1)SAP mm if you're into purchasing, Material Handling, stores etc
2) SAP FICO - finance, audit etc
3) SAP SD - sales and marketing.
Like this, there are plenty of modules.
If you are working then I would suggest that you opt for an SAP module relevant to your job profile or what it is called as domain experience and if you are a freshman then visit Intellipaat.com from where you can do your certification. Google SAP Certification institute and you'll get the list. Rest information institute can provide though you also need to do some analysis find sensible institute as in terms of placements in MNC as a result of in every institute marketing people are hired for attracting more and more students as this is their job so they will try to convince you and will pursue you for doing certification from their institute and that they can guarantee job once finishing certification. Look for good establish the institute and talk to Consultants or the senior students who have done their certification from the institute as they can provide you with a clear picture regarding institute management and system.