This is a good question, as while I was really young bowling on them, I can still remember them.
A lot of points were already made here. To be good on those older patterns, you had to be as versatile as a Gary Dickinson and Dick Weber, but also as much of a technician as Earl Anthony could have ever taught you. That pretty much summarized the 70s as much as I could remember (I didn't first start bowling until '78-'79).
The 80s changed the entire game around. Synthetics, urethane, the entire lot. Kids were able to watch bowling on TV on a saturday afternoon, as well as any local show that featured bowling (Omaha had two such shows; one of which constantly advertised that if you left a 9 count, and the headpin was the only one standing, you'd win a car). And we flocked to it like moths to a flame.
Wanting to be like the people on TV, junior leagues were completely filled at every house in Omaha. Rose bowl in Omaha (second largest house at the time) had so many kids they had to split juniors into 3 shifts. Ames Bowl had 50 lanes but still had to split theirs into 2 shifts, and every lane was used. We only had 3 choices for balls: Rubber, Plastic, or House ball. That is why it was much more of a game of skill then than now.
While I would also say that the early 90s would be my best time (I just turned 18 when the Rhino Pro, Turbo X, and X-Calibur made it big), I would have to go back and say that the late 70s through 1990 was probably the best. That is when it took the most skill, accuracy, versatility, and professionalism to excel at the game. We still had to deal with rubber vs. plastic vs. urethane, but we still had to deal with short vs. long oil and that condition on wood vs. synthetic. Of those 21 houses I mentioned in the Kelley's Hilltop thread, by 1989, 3 were synthetic (IIRC, AFBs have always had synthetic. By 1991, 4 were synthetic (would be 5; Rose Bowl closed at the end of the 1990 season) By that time, it was a challenge to figure out how to keep a urethane ball, let alone reactive resin when it came out, consistent and not erratic due to the hook factor it had on wood lanes, and due to how quickly synthetic lanes dried out at that time.
But the technology made the game easier back then just as it has now. I would love to see a couple of classic leagues our tournaments come up to where ball manufacturers had to put out something back from that level of technology to see people return back to requiring skill for the ball rather than it always hooking out of the box. Won't happen, but I can dream.
Anywho, I would definitely say from 1973 to 1993 would be the best time for bowling.
BL.