CIMA

CMA vs CIMA: An Overview
The CMA qualification is granted by the Institute of Management Accountants and is also known as IMA. CIMA stands for Chartered Institute of Management Accountants, is a designation which comes from the UK.
Membership and Network
Both qualifications were conventional since a long time, but CIMA has a much superior presence with 218K members and students. IMA has around 70,000 members.
Global Presence
In terms of global presence, CIMA conventionally has a more global presence and is well familiar in most places less so in the US but more so in the UK and Commonwealth countries. In current years, the CMA (now CPA) Canada and CMA Australia are getting more widespread in their respective countries so CIMA is disputably less sought after in these countries.
On the other hand, IMA has been vigorously building up its universal presence, remarkably in developing countries e.g. China and the Middle East. For now, CMA is well established in China and is head-to-head with CIMA in the Middle East.
At the same time, CIMA pairs up with AICPA to establish a new qualification known as CGMA. CIMA members can pretty much pay to get the new designation before 2015.
Conclusion
There isn't a superior or simpler qualification. As fellow reader Gunner pointed out in the comment section, while CMA may look easier with only two parts in the exam, it needs a Bachelor degree, vs a high school diploma in CIMA. Or looking at it the other way, as CIMA has a lower entry barrier, it has a more comprehensive exam with extra papers and time/effort in the preparation.
A more important consideration is where you would like to work in a longer term. This will help you select the qualification best suited in that region.