Hi all,
If I go back far enough, it would be a Kodak Brownie Hawkeye, followed by a Argus C3 then a C44.
I had a Yashica D Rolli twin lens that was terrific, too, that I picked up for $12 new in a PX in Vietnam - I used it until the repair bill was $200.
A Mamiya RB67 and the list of Nikons from F, F2, F3, F4, EN, FE2, 6006, a 35Ti, D50, D90, and D7000, and a hand full of consumer cameras (a Pentax weather proof and a Canon point and shoot are stand outs).
The D90 and D7000 share my favorite status, but the FE2 was my favorite camera to use, followed by Rollie twin lens (owned the newspapers where I worked) (or the Yashica D - a workalike).
My best,
Mike