Opinions are like noses, everyone has one, and here's mine. I collect, shoot, and love S&W revolvers. So for someone with limited funds, who wants only one gun, for carry, range, and home protection, I recommend without reservation the:
S&W M&P Shield 9mm.
The Shield 9mm is relatively inexpensive to buy, small enough for carry but not too small, accurate, excellent reliability, and in a relatively inexpensive defense cartridge.
Thanks for considering my humble recommendation.
God bless,
Birdgun