I've only flown CA of the two, and it was between Asia and Europe.
On A332 long-haul, the seat was exactly the same as EK (which I would usually fly these days), same IFE screen too. The pitch was decent, again, definitely not worse than EK, and I'm tall.
As for the IFE, I only ever use it for the flight map. This function worked much better than EK, I could choose from several views and even scroll the map freely, as opposed to screens cycling on their own, which is how it works on most airlines. The interface was much snappier and did not freeze or hang up as is common with EK. Didn't look at what content was available but my impression is that non-Chinese options are limited.
On the other hand, the A333 I took did not have individual IFE but those were short-haul flights in my case. IFE content is still accessible through Wi-Fi, so you can use it with your own laptop or perhaps a tablet, although I'm not sure how it works in practice. Note that phone usage is officially banned throughout the flight.
Seats can be preselected but only in the end of the cabin if you want them for free, the others were priced from 50 CNY (regular seats just closer to the front) to 600 CNY (exit row) extra.
OLCI was theoretically available but broken, I was only able to complete it for one of the four flights I had with CA.
Overall, the flights were decent, although 3 out of 4 got did not arrive on time, with 2 of them delayed ~1h each.
The weakest point was the transfer through PEK, which is disorganized and involves significant and unnecessary queueing: it's difficult to believe that T3 is actually a newly-built terminal, considering how little thought went into its design. On the other hand, my impression of PVG when I transferred there was not really any better. I'd generally avoid transferring anywhere in China if I had the choice.
Overall, the cabin and in-flight experience in Y is not bad at all, and likely to be better than AA/DL/UA. However, considering the unpleasantness of transferring in PEK, the potential for delays and IRROPS, and that dealing with them would be much more of a PITA due to lower customer service standards, I'd only consider flying on Chinese carriers if the fare is < 50% of the non-Chinese competition.
Also, one more thing to consider, especially when travelling with children: the two times I transferred in PEK, the pollution there was simply out of control. The smell of burned coal (as in a building that's on fire) could actually be felt as soon as the plane started its descent. It's difficult to believe people actually live in such conditions. I would be reluctant to transfer there again and definitely wouldn't want to take children there just for this reason.