"AFAIUI" is nowhere even close to as common as your other examples. I have never encountered it before, and Google Trends doesn't even register it in a comparison between the others.
https://trends.google.com/trends/explore?date=all&geo=US&q=a...
https://trends.google.com/trends/explore?date=all&geo=US&q=a...
AFAIK: 8,600,000 AFAICT: 346,000 AFAIUI: 14,600