I'm having major realisations today. If anyone is confused about why sometimes the verb suffix is -ann and sometimes it's -eann, look at the last vowel in the verb root and remember narrow goes with narrow, broad goes with broad! Hence feIc-Eann, but scríObh-Ann for example. Neat!
You would have to define "speakers". Every person in Ireland studies Irish all through their primary and secondary schooling - most of them will use the synthetic form rather than the analytic form. These Irish speakers far outnumber the native speakers, and their level ranges from poor through conversation to fluent. Among native speakers, Ulster speakers generally favour analytic forms, Munster generally favour synthetic forms. Connacht speakers employ a mix of analytic and synthetic forms, but most of the sub dialects probably use muid in this case.
So pick your definition of "speaker", and you can pick your majority.