Most expanding-circle learners choose an inner-circle variety as a target model. For example, in Japan, American English with a GA accent is usually the model. However, having found Taiwan Mandarin a better target model than Beijing Mandarin for my Chinese due to the former's relative lack of neutral tone, I have always felt that an outer-circle variety is a better model for learners of English.
Second-language or creolized varieties are usually easier for learners of English to understand. In terms of phonology, this is partly because of the syllable-timed rhythm. For example, Philippine English has a syllable-timed rhythm. Many languages in the world also have a syllable-timed rhythm. Syllable-timed rhythm is easier for speakers of such languages also because it is a "spelling pronunciation". In many countries, learners learn to how to spell English words before they learn how to pronounce them. Reduction of unaccented syllables in inner-circle varieties of English makes it less orthographically faithful, therefore harder to understand. Speaking English with a syllable-timed rhythm does make you sound less "native-like". But, at the same time, it also makes you more understandable for other non-native speakers. And the majority of English speakers in the world are non-native speakers. Although this may not always be the case, outer-circles speakers also tend to speak more slowly and clearly than inner-circle speakers.
When it comes to grammar, outer-circle varieties are usually more regularized. Intuitively, "I will buy three furnitures for my new house" and "The staffs in that shop are all very friendly" may sound awful for inner-circle ears, but it does seem more logical and regularized for most learners.
According to what I heard recently from a Filipino teacher in Japan, the Philippine English "October ten" for October 10 is much easier for Japanese learners than the American "October tenth", because it is very hard for them to say "th". (Indeed, it is one of the most notorious feature of English pronunciation for most leaners in the world, no matter what their linguistic background may be!)
Maybe this is one of the hidden reasons for the increased popularity among Japanese learners of Filipino teachers and study tours to the Philippines.
