The dominant driver of its value is whether it is awarded by a reputable university with a full-time programme as well.
Agreed. Stick with those accredited by AACSB, EQUIS, or AMBA.
In my opinion, the real value of these programs is more along the lines of that offered by part-time and EMBA programs: you're able to immediately apply the learning to your day-to-day work.
These programs tend to work better when they have on-campus residencies ("blended" delivery, as BigD says.) This adds value in terms of networking and soft skill development.
It's more difficult to compare distance learning and blended programs to traditional full-time MBA programs, in that the latter usually have more potential to dramatically transform careers: many students pursue online MBAs in order to increase their value in their current positions or firms, rather than to completely shift in industries or functional roles.
I'm not convinced that having "Online MBA" on your diploma should make any difference. It's a markedly bad idea to try to fool future employers.