Seat-wise, the CI product is better (1-2-1 instead of 2-2-2), however the CA product is perfectly fine for sleeping (full flat) and the difference isn't THAT much. Both seats are their newest edition of their respective fleets.

When travelling as 2 people together, I'd probably even prefer CA's seats over CIs if you want some interaction..

Point for CI (when travelling alone).. but just barely..

Unfortunately, you don't state the final destination - but coming from Europe, in (almost) all cases to East Asia, PEK will be the shorter flight time all overall. Point for CA (plus an extra half point for better schedule times all overall, as you state)

You've stated that price on CA is cheaper by quite some margin, obviously point for CA too.

Connections via PEK, especially on int-int connections are hardly a problem at all. TPE with it's Taifun-prone region can be much worse in the wrong season (and assuming OP will fly within the next couple months..) - I won't give out points given I don't know the season..

Food and drinks-wise, it really comes down what you prefer. Both carriers aren't THAT good with western dishes on average, but over fairly tasty Chinese dishes. It's down to personal preference I'd say.

Air China has improved a lot in the last years (seat&food-wise) - while China Airlines has (finally as it seems) got their security levels up.

All in all, I would vote for Air China, especially with their ticket being fairly more affordable.