I use 20 gauge for drawing needles. They do take longer than 18 gauge but not too long, and I don't have to worry about too much wear and tear on a 50 cc multi use bottle stopper.
For injecting, I prefer 25 gauge pins for all sites, I use 1 inch for delts and quads, 1 1/2 inch for glutes, and 5/8" for arms.
Harrellmedical.com has good prices for pins but once I placed a large order and instead of shipping it to my box as instructed, they sent it to my billing address (home), in a big TERUMO box with lots of print identifying the contents as syringes. The driver left it on my doorstep. It would have been really uncool if my wife had found it there.