I like the Exa cause it's cute. But it's not the best, by a long chalk. If I ignore my inherent preference for Olympus, I'd go for the Nikon FM2, which looks good and is excellent to use.
However, as is the way of these things, I have to go for Zuikoness, and I'm not sure which gets my vote. I always aspired to an OM-4, and, failing that, the baby 4, the OM2SP, which I now have. But, on reflection, I think I started at the top.
It has to be the OM-1. Everything you need from an SLR, and nothing you don't. With a 40mm f2, it'd be a little gem (and not in a lettuce kinda way).