For me it plays out like this:
Need, 1. For me it's a S&W M&P 9c. I can carry it in almost anything I wear, and if I want to carry it I will wear what I need to in order to do so. It's also got enough capacity to serve as an HD gun and range gun and competition gun.
Now, I would probably stop my collection at:
High End 1911 in .45 ACP
S&W M&P 9 Pro
J Frame Smith in .357
Sig Sauer 938
S&W M&P 9c
That's basically it for handguns. Long guns opens up lots more options.