At any particular point in time, the meter brand of choice was...
Gossen (back in 60's and 70's)
Minolta (back in 80's and 90's)
Sekonic (in the 2000's) -- after they made their meters more like the Minolta user interface and Minolta left the meter market

So on the used market for flashmeters I can highly recommend the Minolta Autometer IV and V, the Minolta Flashmeter V and VI, the Minolta Spotmeter F, which typically get overlooked because today's photographer so often has only heard of the current Sekonics.
Kenko now markets the Autometer V and the Flashmeter VI under their own Kenko brand name and with new model numbers (the Autometer V is now the Kenko 1100).