Whooooaaaaa....Nelly!
If you start with HGs please note that you WILL become addicted. It's a fact of life. Thus, there is no ONE perfect gun, but a multitude of tantalizing tasty morsels begging to be sampled. As such, be prepared to acquire at LEAST one example each of the following:
a) 22LR (either Revolver or Semi-Auto pistol, preferably both)
b) 9X19mm (in a good reliable brand like SIG or Beretta)
c) a "Tupperware Gun" (most likely an HK USP or a GLOCK, to see what the LEO's have)
d) 45ACP in a 1911-type format (many names to choose from to see why the Yanks rave about it)
e) a reliable Magnum revolver (357 or 41 or 44)
f) an historic piece (Inglis HP or WWII 1911 etc...)
g) a SA revolver (who hasn't wanted to be a cowboy, eh?)
h).....and repeat steps a through to g. Hehe.
Honestly, you probably won't own all at the same time, but it behooves you to at LEAST try one example of each.