Open University Malaysia (OUM) offers PhD in Engineering by distance. For those with DETC engineering BS and MS degrees (from schools like Grantham, World College, California National University, etc) who want to terminate their study in engineering, OUM provides a solid opportunity. Check it out here: CGS OUM
I am not sure about the program from a non-English speaking country. I am maybe bias, but I would choose UNISA first....
Malaysia is a Commonwealth country, and English is one of its official languages. Same thing with South Africa, although interestingly English is spoken at home by fewer than 9% of South Africans. So as long as English is the language of scholarship I think you're okay, even if it's not the predominant language you'll hear on the street. I think of it similarly as being in a program at a university in Europe where English is the language of instruction even though it's not that country's main language, like offered by some universities in Scandinavia, Germany, Switzerland, and the Netherlands.
UNISA does not offer PhD in Engineering. They only offer PhD in Computer Science and PhD in Information Systems. Aside from the fact that online PhD in Engineering is a rare-find, if you peruse their faculty pages you'll see that a good percentage of folks who teach there have degrees from top american schools. Further, in some climes, a degree from a school like OUM with many physical learning centers spread around Malaysia and other countries will be taken more seriously than a generic PhD in Business Administration that cost $70k or more from an "american" dot.com school operating from an office space/building. Again, for holders of DETC engineering degrees, this is a super deal (in my opinion), considering that those degrees hardly are considered for entry into doctoral engineering programs. Imagine your name: Engr. Dr. Tekman, with this degree...
Doing a PhD in engineering online is something that sounds really strange. I don't think it would help in any way. It is better to do a regular course only and definitely the best place would be Malaysia. Malaysia is a supportive place for higher studies. And after doing Phd also you would get best resources for research there. PhD would qualify the student for any teaching job worldwide as they are the most respected and preferred ones for teaching.