If you're looking for a plinking round, i.e. something for the range, then go with the 9mm. It will do self defense with the right rounds and trips to the range will be cheaper than the other rounds.
If you're looking for self defense, then I would go with the .40 or .45. I prefer the .45 over the .40 simply because the recoil is less snappy. The .45 tends to have a slow push vs the 9mm +p rounds and .40 rounds that seem to snap the wrist a bit more. I also like the .45 because you don't need "High Pressure" rounds for self defense, so your practice rounds shoot more like your defense rounds.
I have read mixed reviews on hi-point and I'm not sure I would personally get one. I'm also not a huge taurus fan.
I would personally look at the Springfield XD's, Glock's, or S&W M&P series as these are all quality guns. I think you will be happier if you spend some extra cash and get one of these brands vs a cheaper gun. Just go to the store and see which one fits better in your hands.
It's a fact that 70 percent of the people who purchase heavier tackle do so with the categorical I just lost a huge snook! Einstein Hairdo.The other 30 percent have either Tarpon Fever or are sporting a hand cramped into a claw from a deepwater grouper.