The west-coast US/Canadian accent most likely as it's most prominent in popular media, and likely the largest English speaking accent group.

But good luck getting the UK or India to adopt it.

Yu hav too bee bluddy kidding mee if yu fink aim gonna yuz som yanky spellin skeem.

Yu du waht yu havf tu du m8.

All these license plate numbers now finally make sense!!!

type in your own accent, it works when we talk

It sometimes work when we talk.

I believe that there is a lowest common denominator for accented English, and it sounds like “sung” English - which sounds like non-regional American English if the singer is singing and doesn’t naturally have a very pronounced accent. This is partially due to cultural effects but partially due to the mechanics of speaking with an accent.

By “lowest common denominator“, I mean omitting affectations like non-rotic R (Boston) and dropped g (urban) and exaggerated length of selected vowels (US southeast) and constant syllable length and other kinds of things. There are lots of videos on YouTube about how accents work.

But mainly phonetics is about eliminating silent letters, using the most unambiguous letter when there is a choice (eg K or S instead of C), etc.

Anyway I’m rambling but you probably get my point.

Kingsley Read went with something like an artificially rhotic midcentury RP when designing the Shavian alphabet. It works reasonably well for me, a Standard Canadian English speaker, except that distinguishing all the open vowels (father/bought/bot) can be a struggle,