Cheap, relatively smoke-free coated projectiles. Lately SNS and Blue Bullets.
Titegroup for pistols, spherical ball powder for .223
Any brass that isn't cracked or asymmetrically bulged.
Small rifle primers, so that I only need to buy one type. Also beneficial because small rifle primers are frequently cheaper than small pistol primers. I prefer CCI.
I am considering doing something different for major match ammo. Like jacketed projectiles from Precision Delta and sorted range brass. At nationals this year I had a case web blowout that cost me 4-5 seconds delay.