ABC is "Asian Baby Carrier". This would include the Podegi, Hmong, Onbuhimo and Mei Tai. Many people will refer to their MT as an ABC cause it is, but to say ABC doesn't always mean MT.
A MT is a rectangle of fabric with 4 sttraps coming off the corners (all different sizes, shapes, angles, etc). A podage and Hmong just have one top strap, the shape and size of the blanket is different. The Onbuhimo has the top straps but rings on the bottom. You can see all of these variations at the Freehand site www.freehandbaby.com
They are all worn in similar ways (meaning you can wear them on front and back etc.) but they are tied differently and their useage instructions will vary.
There are many "brands" of MT. Many of them do not have the name "mei tai" in their brand name (like Angelpack). There are some brands that do use the term mei tai after the brand name (like Freehand or Ellaroo Mei Tai). Then there are some who have Mei Tai as a prominent part of their name (like Mei Tai Baby Carriers). It can be a bit confusing.
They are all the same type of carrier, worn the same way, but with their own variations. One is not really any more of a mei tai then another, they are all just different. As for which is best . . . preferences vary on this.
You can see many mei tai reviews in the review section of TheBabyWearer www.thebabywearer.com
Most are listed in the Soft Carrier section but there are some in the Traditional Carrier section as well.