I own one of each and they both have their pluses and would vote for both. The biggest plus to the Mei Tai is it is more adjustable if you are plus sized and bumpy. DH can get the Ergo much more snug to his body than I can because of all my lumps
. Because I can adjust the MT snugger it is more comfortable to wear long stretches. Although for shorter trips they are about even. The Ergo is quicker to put on and easier to back carry when you are alone. The Mei Tai straps drag on the ground when you are putting it on which is a PITA when the ground is wet. DH hasn't tried the MT so I don't know if he likes it as much as the Ergo.
ETA one more thing. The back of the Ergo is shorter than the Babyhawk so DS doesn't have as much seat in the back. I have heard some moms prefer that. Personally I like the high back to the MT because it is better for naps. That flap thingy on the Ergo is really silly.
ETA again I didn't use my Ergo with a newborn I got it when DD was 6 months. I have no opinion on the infant insert.