I've done zed on all the carrier's ive listed. All with exception of lot are easy to list and check in. I like to avoid Heathrow especially if connecting. Though the train to Paris is easy. Swiss has the best travel experience of the ones you've listed and Zurich is an easy airport to make connections. Also there are trains from Zurich to Paris. Klm and lufthansa are good carriers. With a family in the summer I would buy Zed's and plan train travel once over there.
British Airways
Finnair
KLM
LOT
Lufthansa
Swiss