I think AA's angled lie-flats are comfortable - amongst the most comfortable angled lie flats I've flown on. That said, I still prefer lie-flat.

The other thing you get with the lie flat config is better IFE and proper AC power (important if you have a beefy laptop). Old C relies on tablets for IFE and uses the old cigarette lighter DC power, capped at 75w. So there are more factors than just the seat to consider.

If I were in your shoes, I'd pony up for the lie flats. However, if my choice were angled seats vs Y, I'd have no qualms about paying for old C.