Lately, a lot of people tout the Technics 1500, but ask the folks who own them, and what they paid for modding-repairing them, and the numbers will stagger you. The Technics 1500 is no simple machine, is quirky and being that there are few who can put them back in shape, expect to pay dearly.
Simple answers, TEAC 3300 in various flavors, even 2-track. 3340, 3440, and another very beautiful machine, but might be costly, as it is rare, and who could ever find parts for, is the Fostex E3/E4 machines.
Akai's were nice, and common, but again, all of these machines have little to no support via company. make sure you know qhat your buying before you open your wallet. Mark