I'm not sure I agree, but I'm still really new to Threezero.
I think both companies do good sculpts but both also struggle with their paint application, which holds the sculpt back. Although both have been improving but they're not at Hot Toys level.
Asmus does better quality accessories (metal/fine details) and Threezero seems to have better outfit work, that said the level of detail and care Asmus puts into their armor figures is incredible. The armor work on Eomer/Theoden/Last Alliance warriors is second to none, although this Lannister armor may come close when I see it in hand.