This is a question much like that asked of model railroaders.
HO has the most "stuff." While O is a bit easier to detail & run (and lets you tap into HO via On3).
And, you also have the choice of N & Z if you are keen on microscopes.
Or, like over in Ships. For steel hulls, the two 'real' choices are 1/350 and 1/700--except that there are also 1/600 and 1/400 lines; pluse the middling new offerings in 1/200, 1/144, and some in 1/72.
In sailing vessels, it's 1/96 & 1/100, then down to 1/150 and smaller.
Best method seems to be in picking what you like, and enjoying it.
I used to thing those folk working in 1/24-1/25 and 1/16 were a committed bunch--that it until I saw how the 1/6 community has taken off.