23 is all around a great gauge.
I personally draw with a 1.5" 21g, then pin with a 1.5" 25g. I try not to use the same pin for drawing/pinning because it does get a bit dull going through the rubber.
23g 1.5" would be fine for everything, if you want to simplify it.
I use 1.5's whether its delt or glute. If you have smaller delts, you can use 1"
It takes a minute to push out the oil with a 25g but its fine. Once you become limber enough, you can hit glutes no prob. Just takes a strong thumb. Sometimes i have to stop for a sec, get the cramp out of my thumb, then continue pushing.
EDIT: my first cycle, i used only 21's to draw and pin. The same needle btw. No changing. That sh*t was brutal.