If you want to reach the pinnacle of your profession (fame + $$$$) and are prepared to do the work (creative and personal) to ascend those heights, LA or NY is WHERE THE MAJORITY OF THE BIG TIME WORK IS. Notwithstanding that quite of bit of excellent acting/actors and big time work occur in many other and smaller cities in America...but...if you want to get into the big-time
oil business in America, you go to Texas, you want the big-time
potato farms, you go to Idaho, if you want to get into the the big-time
acting business you go to LA or New York. Like it or not, most major producers are functioning in those cities, most big time casting directors, most extraordinary acting teachers, most higher levels of salary occur there. It is where the action is. Unfortunately, it is also where the major competition is: there are more good actors in those two cities than anywhere else in the US. In designing your career ladder, decide how high you need to climb; only then head for the rung you need to be on.
If you must go to NY or LA, the old rule of thumb was: before venturing to NY or LA first become the best actor in your local area; then the best actor in your sub-regional area; then the best in your regional area; then go to New York or LA. Like professional sports: the best sandlot football players get on the high school team, the best high school football players go to college, the best college players make the pros. However, rules are 'average' wisdom: rules for the 'average' apply. But we actors think we are exceptional; we defy the rules.
If you decide to go early to LA or NY, consider these factors: (1) life style changes. Who are you leaving behind, and how much is that going to cost you psychologically and emotionally. For each new choice there is a commensurate cost. (2) Are you ready for the lonliness? Nothing is lonlier than a being a stranger in a crowded town. (3) Are you ready for competetion? LA was once described as six million ambitious people pretending to be laid back. (4) Are you prepared for an increased cost of living? A probable general raise in prices, plus apartment, head shots, transportation, phone service(s), etc. (5) Do you have a job lined up before you get there, or do you have a new egg built up before to live on until you get a job. Another 'average' rule: don't expect to make any appreciable acting$$$ for the first two years. (5) Are you prepared to work hard on your acting craft? No matter how good you are, you are going to have to get better. Even if you are ahead of your competitors, you will only stay ahead of them if you work harder than them...otherwise they will catch up.
Finally, go to either town with the idea of adventure. It is a life journey, a career journey. And like most journeys, pleasure occurs more in the process, in the courageous headlong attempt, than in any final achievement. And good luck.