Well to tell you honestly as far as my research goes sheffield and Jeppesen are both equally good if u consider their benefits..
If u have are legally staying in US n u do your course through sheffield its easy to get a job with FAA license ... but if you wanna work in the middle east then i believe GCAA license is very useful and handy.... GCAA license holders can go to states and give a reexam as u might have read to get a FAA license... u dnt have to repeat the six weeks again
At last how u get it is completely dependent on ....
i m not much of an aviation expert ... just a small fish .. but have done the dispatch course through jeppesen recently .... and found it very interesting n challenging
I hope this info is of some use to you