Affordable, English speaking with good opportunities. What city do you recommend with these factors?

I think your options will be either India, where the cost of living is pretty low and most business is done in English.

Or maybe Cape Town/Johannesburg in South Africa.

Major cities in South East Asia, like Kuala Lumpur or Jakarta are similar. But, while most people understand and use English, it might not be as common as the two options above.

Other possibilities include major metropolitan cities in countries with comparatively lesser cost of living, like Ankara in Turkey or Buenos Aires in Argentina.

Of course, each of these options comes with its own set of challenges, and the kind of work you're into should also be factored in.