Good one! Honestly I wish Subaru sold the 86 and Toyota sold the BRZ -- or something else. Or nothing at all.
I rather have a Subaru badge because: the car is 90% Subaru and actually manufactured by them; despite my own poor experiences with Subaru service departments, I'd trust them more than Toyota with this car; and I trust Subaru corporate more than Toyota corporate.
But I'd have a really hard time getting over the Subaru front grill and the red striping in the interior. It's all just personal preference, not a matter of objective right and wrong, but I love the 86 front end and actively dislike the Subaru one. And I'd feel a bit embarrassed every time I looked at those boy-racer trying-too-hard red stripes on the BRZ's seats.
While I appreciate the pros and cons, I'd also err on the side that Toyota took with the handling dynamics. And their choices with the instrument panel seem a bit better too.
So give me the 86 but branded as a Subaru!
EDIT: Not likely to happen, but Ive fantasized a bit about getting a second twin, this time an AT. If so I'd go for the BRZ. Wouldn't it be sweet to have a MT 86 and an AT BRZ! Given the suspension choices Subaru made, and the less sporty (to me) front end, it seems like the best twin for an AT!