I teach maths so I have a preference for Edexcel, but to be honest there is very little difference; ( although there are more free resources for Edexcel online)-you may find that you have to do one or the other if the centre you are using only offers one exam board. For IGCSE English the Edexcel one I listed 4EB0 is the obvious option if you aren't following a course as there is no point in making it more difficult for yourself. Unis won't care which you do