Congratulations on the purchase of your first gun, it sounds like you are off to a good start with a G23.
For Home Defense purposes I would concentrate on the bullet nose design rather than bullet weight, and in that case I would choose a high quality Hollow Point. There are others on the forum who will probably respond to this post with good advice about which Hollow Point to use. For Home Defense I use my G17 (9mm) carrying 124-grain Jacketed Hollow Point ammunition.
I use 180-grain Winchester "White Box" (also known as "WWB") Q4238 full metal jacket .40 Smith & Wesson ammunition for USPSA competition shooting. It has a little less velocity than their 165-grain ammunition (marked "USA40SW"), which I find to be a little "snappy" and uncomfortable to shoot.
We commonly use a term called "Power Factor" to describe basic ammunition power. The formula for Power Factor is W x V/1,000, where W is the bullet weight in grains, and V is muzzle velocity in feet per second. That gives us a number that we can use to compare the recoil energy generated by the ammunition as well as a rough idea of its hitting power.
The 180-grain ammo I mentioned has a velocity of 1,020 FPS, for a Power Factor of 183.6. The 165-grain ammo has a velocity of 1,060 FPS for a power factor of 174.9. Even though the 180-grain I prefer has a higher Power Factor, it feels better to me in my gun (a G35), which has a compensator.