And Griffin Avid - agreed - the ads in both vintage and newer mags are great. For me its the logos - Moog. ARP. Oberheim especially.
And the artwork - like in that SCI ad above. John Mattos was the artist for a lot of those classic Prophet SCI ads. Really helped build the SCI brand. You even see those ads framed in the background of a lot of the photos of Dave Smith in his office/studio. Classics.
i used to collect the ads of synths i have actually owned. Kind of like some stupid notch on the belt type thing. I have a micromoog ad and a prophet 10 ad. If i find them, i repost here and see if someone wants them(for free obv).