Recognizing that you may get a switch to the A350, the Finnair A330s that often fly these segments have 2-4-2 seating throughout Y and a more comfortable seat width compared to AA's more dense 3-4-3 777 cabin (18 in vs. 17.1 in or even less in Exit) so if you are able to get an extra legroom seat on AY, you're going to have a more comfortable Y trip than AA in MCE (just my own experience). The A350 is marginally tighter but still a wider Y seat than the AA 777s (the A350's the quietest aircraft cabin between the three).

I'd prefer a break in this journey myself if flying in Y compared to the AA non-stop. HEL is an easy airport to connect in and the AY lounge(s) there are decent.

I'm not a fan of connecting in DOH even if flying in J.