My memories of synthesizers go back to the famous RCA tube-type instrument, particularly the Mark II incarnation installed at the Columbia-Princeton studio in 1959, where it was employed by such composers as Babbitt. For a complete demo of this instrument, get hold of RCA Victor Experimental Album LM-1922, "Sounds and Music of the RCA Electronic Music Synthesizer."
Other famous "fifties" (tube-type) efforts include the Barron soundtrack to the movie
Forbidden Planet. This is an iconic electronic music work, the first electronic music film soundtrack, and it was never matched.
In those days, electronic music was mostly the province of a few dedicated studios such as the Cologne Radio studio in Germany, where such composers as Stockhausen plied their trade. To get an idea of what could be done with such studios, get Stockhausen,
Electronic Music (Deutsche Grammophon 138811).
Bob Moog was on the scene by the mid-sixties with his first modular instruments (ARP was hard on his heels with their famous 2500 modular synth). These were classic "analog" (subtractive) synths, and they set the basic technological style for most synths up to Yamaha's DX-7 in 1983. The album which probably did the most to bring the name of Moog before the public was Wendy Carlos,
Switched-on Bach (which I must admit I never cared for). Synths capable of use onstage began with Moog's Minimoog and ARP's 2600 and Odyssey, all from the early 1970's.
Meanwhile, Don Buchla on the West Coast was going his own way, building his own particular breed of synths, and moving generally in the opposite direction from Moog and ARP. His instruments became the favorites of such composers as Subotnick; a good perspective on the Buchla synths is available with
Silver Apples of the Moon, Nonesuch H-71174.
Other names from the era include those of Tom Oberheim and Dave Smith (of Oberheim and Sequential Circuits; remember the "Four-Voice" and the Prophet?). Shortly after their advent, however, Yamaha mated Dr. John Chowning's development of FM sound synthesis to their legendary DX-7 (my favorite keyboard to this day), and shattered the analog-synth monopoly of the market. And after that, developments came quickly from several different directions.
However, the classic "analog synth," as noted above, is still capable of things that no later technology style could match (each of those styles, in turn, is likewise capable of unique things).
If you really want a comprehensive and thoroughly engaging idea of what a complete and well-managed modular analog synth rig can do, get hold of Isao Tomita's albums
Snowflakes are Dancing (RCA Red Seal ARL-1-0488) and
Bermuda Triangle (RCA Red Seal ARL-1-2885). Tomita produced other albums, but these are the two most illustrative (and arguably the two most enjoyable).
Always glad to discover others who are interested in electronic music, and hope this helps.

Larry