I'd say flats of some variety, or rounds with the tone knob rolled way back. Hard to tell without a closeup of headstock, or some specific defined tone to focus in on.
And you're going to get widely varied responses to this just because the definition of Flat tone and Roundwound tone is pretty wide depending on what brand of each type you play.
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Lakland Skyline 55-01, Fender G Lee Jazz Bass, 1984 Squier P-Bass, Epi T - Bird Club Member #47, Peavey Firebass 700, Ampeg SVT610HLF Cab, Line 6 PODxt Live