I'm a regular LH flyer, but having to choose a carrier for a flight down from NA to GRU.

I can fly ORD-GRU with UA on an old 767 in their Global First seat or fly YYZ-GRU with AC on the newer 787 in Business. (My flight is in Dec when AC has the 787 on this route.)

I'm mainly interested in the seat and getting a great rest. Less concerned about catering.

What would you do?!

Thanks!