Started out using 23g to pin. Switched over to 25g for pinning, 1.5 inch for glutes and 5/8 for delts. Smaller gauge goes in much smoother, but I noticed that when my hand wasn't super steady pinning glutes, it wasn't as firmly planted and moved around a bit, which caused greater PIP the next day.
Drawing with 23g is slower than 18g, but that extra few seconds doesn't really matter. And if you use proper technique when piercing the rubber stopper, you can't tell the difference between a 18g and 23g hole, and no rubber pieces floating.