Yes, from hard- and software aspects, pretty much my priority rank too. But adding the comfort aspect too, QR adds a middle.of-the-night connection. Haven't checked DUB-HEL-TYO connections, but generally HEL is an extremely easy airport for connections, MCT 35 min! The HEL approach can be used for both AY and JL, who also cover HEL. Connecting [MENTION=128682]LHR[/MENTION] will include terminal transfer T5->T3 for CX and JL, but not for BA. Not a big obstacle, really, but I would still weigh that in.

Good luck in finding the flights/seats you fancy, and enjoy friendly and polite (understatement) Japan !