Hello Hoodjem,
thank you for the greetings,
once again I shall split my answer because I write more than 10000 characters. Here is the first part of my message
Here is my list of the 4 most important events of each year since 1950. I haven't checked it for more than a year and at the time I've taken into account some Jeffrey Neave's remarks (in the Wikipedia site). SgtJohn proposed to include some clay events in the 50's to be fair with modern players but in a Tennis Warehouse quote I retorted that in this case we should pick up modern events on truly fast courts to be fair with ancient players because nowadays fast courts almost don't exist anymore.
My "not recently updated" list :
Here is at last my personal list of the 4 biggest events (in disorder when no ranking is indicated) year by year from 1950 to 2007 (changed on Thursday September 27, 2007 after Jeffrey Neave’s remarks) :
1950 : 1) the Kramer-Gonzales pro tour, the US Pro (Cleveland), Philadelphia Pro, 4) perhaps Paris Pro indoors or the beginning of the Kramer-Segura pro tour (ended in 1951) or even Wembley Pro
1951 : the U.S. Pro (held that year at Forest Hills, the usual site of the amateur championships), Philadelphia Pro, the main part of the Kramer-Segura pro tour, 4) Wembley Pro (or the German Pro in Berlin)
1952 : 1) Wembley Pro, 2) the U.S. Pro (Cleveland-Lakewood) and Philadelphia Pro, 4) Berlin Pro-Rot Weiss Tennis Club
1953 : 1) Wembley Pro, 2) the Kramer-Sedgman pro tour, 3) probably the Paris Pro tournament, the New York Pro Indoors, the Caracas and Lyon (and perhaps Geneva) pro tournaments (very difficult to know what were the greatest events that year : the tournaments cited here are the only ones where three of the four best players were present each time)
1954 : 1) the US Pro (Cleveland), 2) the Australian Pro, 3) the Gonzales-Segura-Sedgman-Budge (and Earn) pro tour, 4) the Australian Gonzales-Sedgman-Segura-McGregor pro tour or the US Pro Hardcourt (Los Angeles) or the Far East Segura-Gonzales-Sedgman-Kramer pro tour
1955 : 1) the US Pro (Cleveland), 2) the Australian Gonzales-Sedgman-Segura-Ayre pro tour, 3) the US Pro Hardcourt (Los Angeles), 4) perhaps Scarborough Pro (or even the several pro matches in Rome with Gonzales-Sedgman-Segura-McGregor in June)
1956 : 1) Wembley Pro, 2) the first Pro Tournament of Champions at Los Angeles (not held at Forest Hills that year), 3) the US Pro (Cleveland) and the French Pro (Roland Garros)
1957 : 1) the Pro Tournament of Champions (Forest Hills), 2) the Masters Round Robin Pro in Los Angeles, 3) the Australian Pro (Sydney), 4) the U.S. Pro (Cleveland) (5) Wembley Pro).
1958 : 1) the Pro Tournament of Champions (Forest Hills), 2) Wembley Pro, 3) the French Pro (Roland Garros), 4) Masters Round Robin Pro in Los Angeles or Melbourne Pro or the Australian Pro (Sydney, there were only 3 Australian Pro in tennis history, 1954-1957-1958 )
1959 : 1) the Pro Tournament of Champions (Forest Hills), 2) [New South Wales Pro-Sydney (the February edition), Victoria Pro-Melbourne, South Australia Pro-Adelaide, Western Australia Pro-Perth, Masters Round Robin Pro-Los Angeles] with all the best players and perhaps tied with Wembley Pro and the French Pro because the two last had a (small) tradition but Gonzales, then probably the best player in the world, was missing both tournaments due to his legitimate dispute with Kramer now mainly a pro tennis promoter
1960 : 1) the Gonzales-Rosewall-Segura-Olmedo pro tour, 2) Wembley Pro, 3) the French Pro (Roland Garros), far behind 4) the Australian Pro Indoor in Melbourne in May (not to confuse with the Victorian Pro in Melbourne in January) or Santa Barbara Pro (or perhaps the Masters Round Robin Pro in Los Angeles or San Francisco Pro ?)
1961 : 1) Wembley Pro, 2) the French Pro (Roland Garros), far behind 3) Vienna Pro and the Scandinavian Pro-Copenhagen
1962 : 1) Wembley Pro, 2) the French Pro (Roland Garros), far behind 3) Geneva Pro and Milan Pro (and perhaps the Kramer Cup ?)
1963 : 1) Wembley Pro, 2) the French Pro (Coubertin), enough far behind 3) the U.S. Pro-Forest Hills, 4) Kitzbühel Pro and Cannes Pro
1964 : 1) Wembley Pro, 2) the French Pro (Coubertin), 3) the US Pro (without Sedgman, present in the two big European tournaments), far behind 4) the US Pro Indoor-White Plains ( 5) Masters Round Robin Pro-Los Angeles and St Louis Pro, 6) College Park Pro)
1965 : 1) Wembley Pro (without Gonzales), 2) the US Pro (without Gimeno) and the French Pro (Coubertin) (without Gonzales), far behind 4) the US Pro Indoor-New York City (without Hoad) or the Victorian Pro-Melbourne (without Gimeno) or the New South Wales Pro-Sydney (without Gimeno)
1966 : 1) New York City-Madison Square Garden Pro, 2) the US Pro, 3) Wembley Pro and the French Pro (Coubertin) (5) Pro Clay Court Championship-Barcelona and possibly Forest Hills Pro)
1967 : 1) Wimbledon Pro (possibly the most important pro tournament in the pre-open era though with a reduced field of 8 players), 2) the US Pro (the strongest field of the year), 3) Wembley Pro and the French Pro (Coubertin), ( 5) Los Angeles Pro, 6) New York City-Madison Square Garden Pro and Berkeley Pro).
In the open era until 1982 included the hierarchy was almost as unstable as in the pre-open era :
1968 : 1) Wimbledon Open, 2) the U.S. Open, 3) Roland Garros Open (many players couldn’t come because of the events of May 1968 and Dave Dixon, boss of WCT prevented his players to enter the tournament : among the best claycourt players absent were Newcombe, Roche, Okker and Santana) and the Pacific Southwest Open in Los Angeles (all the best were there) (5) US Pro, French Pro, Wembley Pro and possibly the Queen's)
1969 : 1) Wimbledon Open, 2) the U.S. Open, 3) Roland Garros Open, 4) the Australian Open (5) the Pacific Southwest Open in Los Angeles or the Howard Hughes Open at Las Vegas or the Philadelphia Open or perhaps the South African Open or the German Open or the Italian Open)
1970 : 1) Wimbledon Open, 2) the U.S. Open, far behind 3) Philadelphia Open, 4) Dunlop Open Sydney (5) the Masters (the first one in tennis history, at Tokyo), the US Pro (Boston), Pacific Southwest Open of Los Angeles and Wembley Pro. I haven't yet a clear opinion between all these events).
1971 : 1) Wimbledon Open, 2) the U.S. Open, 3) the Australian Open, 4) the WCT Finals-Houston&Dallas or the Italian Open (Rome) here is our major disagreement between jeffreyneave and me : he thinks that Rome is above the WCT Finals that year, I originally thought the contrary but after his arguments I changed a little my thinking and placed both tournaments equal)
1972 : 1) the U.S. Open and far behind 2) the Pacific Southwest Open in Los Angeles (the 2nd best field of all the events after the U.S. Open because both WCT and independent professionals could (and would) enter) - the WCT Finals-Dallas, 4) the Stockholm Open (3rd field of the year) and perhaps the Davis Cup. Recall : no pro player under contract (WCT) could enter the Davis Cup, Wimbledon and Roland Garros because they were banned from the traditional circuit from January through summer (the first « open » tournaments in 1972 were Merion and Orange just before the U.S. Open) : during Wimbledon, Newcombe, a WCT player in 1972, won the St. Louis WCT tournament, not at all a Grand Prix tournament (the Grand Prix circuit was the traditional one) as wrongly indicated in the ATP Website and then commented the Wimbledon final on TV whereas he was the titlist.
1973 : 1) the U.S. Open 2) Roland Garros Open and far behind 3) the Masters, 4) the Italian Open-Rome and the WCT Finals-Dallas ( 6) the first Davis Cup Open to all professionals and in particular the WCT players (I think , but I can be wrong, that if the Challenge Round system had been abandoned in the 50s and not in 1972 and if the Davis Cup had been open since 1968 (and eventually before) and not since 1973 it would possibly have still been the greatest tennis event today)
1974 : 1) Wimbledon Open, 2) the U.S. Open, far behind 3) Roland Garros Open, 4) the WCT Finals-Dallas (5) the Masters or the US Pro indoor-Philadelphia)
1975 : 1) Wimbledon Open, 2) the U.S. Open, far behind 3) Roland Garros Open, 4) the Masters ( 5) the WCT Finals-Dallas)
1976 : 1) Wimbledon Open, 2) the U.S. Open, far behind 3) Roland Garros Open, far behind 4) the U.S. Pro Indoor-Philadelphia (and perhaps the WCT Finals-Dallas)
1977 : 1) Wimbledon Open, 2) the U.S. Open, far behind 3) the Masters, 4) Roland Garros Open ( 5) perhaps the U.S. Pro Indoor-Philadelphia and the WCT Finals-Dallas)
1978 : 1) Wimbledon Open, 2) the U.S. Open, far behind 3) Roland Garros Open, 4) the U.S. Pro Indoor-Philadelphia
1979 : 1) Wimbledon Open, 2) the U.S. Open, 3) Roland Garros Open, and far behind 4) the Masters (5) the WCT Finals-Dallas)
1980 : 1) Wimbledon Open, 2) the U.S. Open, 3) Roland Garros Open, and far behind 4) the Masters
1981 : 1) Wimbledon Open, 2) the U.S. Open, 3) Roland Garros Open, and far behind 4) the Masters (5) the Davis Cup)
1982 : 1) Wimbledon Open, 2) the U.S. Open and Roland Garros Open, and far behind 4) the Masters (5) the Davis Cup)
1983-1985 : 1) Wimbledon Open, 2) the U.S. Open and Roland Garros Open, and enough far behind 4) the Australian Open ( 5) the Masters)
1986 : 1) Wimbledon Open, 2) the U.S. Open and Roland Garros Open, and enough far behind 4) the Masters (in December)
1987-2007 : 1) Wimbledon Open, 2) the U.S. Open and Roland Garros Open, 4) the Australian Open ( 5) the Masters).