If I'm not camping in the Church stairs with the barricades still blocking the doorway, I'm training either near the Death Ray or in front of the Church.
I like the Death Ray spot more because I have several outlets pf survival - one insta-kill trap (and protector when the Panzer rolls in), a Launch Pad to another great training spot (Rocket Test Site), three possible exits, and a potential PaP machine. It's very close though so you're be blowing through your ammo consistently. If I'm running this spot, I like to have an MP5 as my point-whoring weapon.
There is a circular area in front of the church that also works pretty well, with the same benefits as the Death Ray route. This one is tougher in my opinion because while you have a larger radius to control your trains in, the zombie spawns are positioned in such a way that you're bound to get blocked. This is why you absolutely need an upgraded Bow; nothing is worse than seeing that tiny path between a wall and the center debris closed off by two crawlers.
And honestly, the pyramid room is insanely tough to train in. When the anti-gravity kicks in, you can't exactly jump over the zombies since they'll Shaq-attack your ass immediately.