I have two JM Marlins and two REP Marlins, the REP Marlins have better metal work, seem to shoot and cycle better overall and the wood/stock while not bad is an area to improve yet perhaps. Mine are 2016ish manufacture. My JMs are 1973 and 1982.
I would not purchase for top dollar a Marlin of any era without it being vouched for. Marlin, despite the mythology that has sprung up since they sold to Remington, have had long standing quality and function issues including all the currents ones, barrel droop, crooked sights, wrong sights, Marlin Jam etc. Yeah, I guess the wood was mostly better though for them. Even if the sights were crooked.