I'm more in tune with the Supra's shape.. I don't know how much the Bimmer version costs, but if I am spending $70K+ range, no question I would definitely get a Cayman with the MT gearbox. I want something that looks out of the ordinary (since I already have ordinary cars) and the new Supra is definitely uniquely shaped. I only struggle that it only comes with AT, but if it's a garage queen where I only take the car out a few times during the season, I guess who cares.
Cool, I have not driven the Supra/Z4, but I have had Z3/Z4's in the past and they are solid roadsters, I would think the new one is going to be pretty good, BUT, if you are inclined to go with a Cayman, I would def steer you in that direction, I have had all kinds of cars and that tops a VERY long list.
Also, I bought my Cayman (as I do most of my cars) a year old with 3500 miles. It had 8k in exclusive options, makassar wood trim, painted gauge faces etc..., so I go at 74k sticker for 52k, I would recommend that path to anyone interested in a Pcar, all of the Boxsters and 911 were older and I paid cash for them, they are just as fun..... people never know how new or old they are...
I drove a GTS PDK Cayman a couple months ago, first time in the four banger, it was dope, I drove a year old 911 immediately after, it was a manual which was cool and starting to become pretty rare, but still strongly preferred the Cayman.