First of all, there's no BEST in these platforms. It's all about indexing. If you publish your article(s) in well reputed journals, surely these are indexed both by RG and Google Scholars. From my observation, Google Scholar indexed wide range of journals (publishers) compare to RG. In some cases, RG is bit conservative but they are indexing those journals which are SCI indexed (in some cases most Scopus indexed as well).