Its really hard, to choose one over the other. Both are lovely piece of engineering and offer similar kill capability.
The recent close up pix of the Z-19 and Z-10 show remarkable engineering. It is clear that each piece, each element, each panels, wings, weapons etc were designed to fit like a glove and the gleaming, built like a merecedes machines hint at the capability inside.
The only question marks, which I think the chinese have dispelled is how reliable are the engines and the overall structure, how much technology it has and what weapon loads and other inventory it can use. The platorms are not mature but are getting there very quickly.
The T-129 offers many things, it comes from the Augusta-Westland stable - and their ponies are world class, extremely reliable and tough. You can rely on them. However, there is a cost disadvantage, 1 T-129 may equal 2 Z-10s, and numbers do matter, the technology will be world class, including the radars, FLIRS and other detection systems. The safety of the crew is paramount so the system will be designed to be reliable but in case of a failure the ****-pit offers are very robust shell to survive a hard landing. Yet due to globalisation this gunship relies on parts from different countries, countries that can veto either the sale or veto their parts in the future.
Hence it is a tough choice, I love what teh Turks have produced and want to diversify my suppliers but the Z-10 is also a great option, either one is still a winning choice for the PAA.