2 questions.
Which is the best VM size in terms of ROI? i am using 4 cpu 16 gig servers.
What region is the best for placing my Azure VM? Does this make a difference to speed? I am currently in SNG datacenter and SNG has traditionally had a very quick internet pipe.
You won't get a ROI with Azure, nor with AWS or anything else. The "cloud" has to be made up of ASICs, not general purpose type machines.
The region is only useful for Web or other applications that either need a specific data centre for regulatory or other requirements, or for fail-over, replication, backup and other reasons. SNG is not bad, for example, if you want your data and services out of US or FVEYES jurisdiction.