If you get 5 answers, you'll have 5 different suggestions. Check the ballistics reports on some top brands - Corbon, Winchester, Speer, Hornady, etc. When you find a round with the characteristics you like, get a box and see how your gun and you like it. Does it feed and eject reliably? Does it shoot to POA and are YOU accurate with it in YOUR weapon? If the answer to all is "yes", then go with it.
Personally, my favorites are:
.40 S&W - Corbon DPX,
140 gr.
HP
1200 fps
448 ft.lbs
9mm - Corbon DPX +p
115 gr.
HP
1250 fps
399 ft/lbs
.380 ACP - Corbon DPX
80 gr.
HP
1050 fps
196 ft/lbs
.38 spcl. - Hornady Critical Defense +p
110 gr.
HP
1270 fps
394 ft/lbs
My wife likes:
.32 ACP - Fiocchi XTP
60 gr.
HP
1000fps
133 ft/lbs
I'm always open to other suggestions with ballistics specs.