I think the more important question would be how CX fares against the current competition, rather than against how CX was 15 years ago; since the choice is what to fly now, and overall there has been a noticeable decrease in service levels globally.

Status: Having status, especially DM, on CX is still very valuable. The things you listed - redemption availability, customer service, all-around on board experience - is still very good for a DM, and I would consider it to be among the best in the world.

Hardware: Admittedly, hardware is lacking a bit, I was recently on some old 330's to TPE both ways, but when you compare it to BR's 320's where I didn't even have a TV on a narrowbody, and I would much prefer CX.

Bags / flight delays: Honestly I will still rank CX as among the best in the world. They did have high profile flight delays and cancellations, but those are rather one-offs, and much better than any Western competitor.

Lounges: Still good but I find them to be a lot busier than before, perhaps due to the fact that many credit card holders will get X number of lounge passes per year.

Service: Worse than before - especially in Y - but among the best in the world in 2024. Based on the other airlines you fly on, it will be a world of difference versus AA and UA.

VS other Taiwanese airlines: I put CX above CI and BR; I have only heard great things about JX but have not flown with them personally. Service as a DM is better than top tier on CI/BR; service as a no status, economy flyer is way better than being no status and economy on CI/BR.

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TL;DR Summary: CX service and reliability isn't as good as 15 years ago but still rank among the best in the world, since service standards and reliability globally has sadly fallen. I find them better than all Western and ME carriers (controversial but just my view), and I think they are in the top 5 with SQ, JL, NH, and perhaps JX.