If you are playing Horde mode then my choice is "River."

You can head to one of the 2 houses it does not matter, preferably the side you spawn on.

When you get into the high 20s and up head inside the house and wait for a mauler to charge up the steps and be sure to ether use a grenade trap or use your gorgon pistol to stop him.

Pick up his shield and mount it on the ramp.

No one will be able to get through it.

Just make sure the bloodmounts don't knock it down.

After each wave pick it up until everything from the last round respawns.

Then set it up and Horde the Horde!